Volume 29 (1874) (428 pages)

July 25, 1874-] 5] MINING AND SCIENTIFIC PRESS. SciENTIFIC (PRocREss. Celocity of Nervous Impulses, However slow the rate of nervous movomsent mey be, as compared with the velocity of light or tbe atill feeter anotion of electricity, it is neverthelees so rapid that until qnite recently it was thonght to immeusurable, within the limited range in which onr observation of it is possible. The most widely aeparated points in the course of any nerve allow hut a few feet of difference at hoat for timing the periods of sen. sation or volition; and the nervous impulse travels so qnickly that snch small distances wonld seem to he wholly annihilated, To our concionsness a prick on the groat toe is discovored ns promptly as one on the cheek; and it is only by the intervention ot the most delicate and ingenions of meohanical contrivances that the difference in time is made apparent. In all the early experiments on motor nerves, the leg of n frog bad heen nsed. In 1867, Baxt and Helmholtz applied the test to man, nsing an improvement of the myogrsphicon suggested by Dn Boie Raymond. Tbe resnit gave the rate of condnetion for the motor nerves of man, corrosponding to that already obtained by Hirsch forthe sensory nerves, A very oareful seriea of experiments by the same observers, in the summer of 1869, showsd a mean rapidity for the motor nerves in man very mnch greater, or about 254 feet a second. The measnrement of the rate at which the nervous impnise travels hrainward necessarily involves a process very different from any employed inthe stndy of motor nerves. The problem wss first attacked by the Swiss astronomer, Dr, Hirsch, soon after Helmholtz took np tbe other branoh of the investigation, and his solution of it was as ingenions as it was suoeessfnl. It involved the measnrement, with the delicate ohronometric instruments employed by astronomers, of tbe difference in time hetween the appreciation of impressions made at a distance from the hrain, say on the great toe, and others nearer, as on the cheek. Ronghly deseribed, the plan adopted wae substantially this: The ohserver sat with his finger on a signal key, with which he announced the perception of an electrio shock as soon as possible after feeling it, thns closing an electric circnit which had heen broken by theshock. The min. nte interval between the breaking and closing of the cirenit measured the time taken hy the trsnamission of tbe shock to the brain, thetime reqnired for the perception of the sensation, time for willing the movementof the signal key, time for the transmission of this volition to the proper mnscles, time for the contraction of the musoles, and finally the time lost in tho physical process of eignaling. Obvionsly all these parts, except the first, must he substantially the same in all experiments by the eame person, nsing the saine finger for making the signal. Any difference in the whole time must therefore be owing to the greatsr or smaller distance of the partivnlar point of impression from the brain. This difference being measured with tolerable exactness, it is possible to calcnlate pretty closely the rate at which the nervons impnise is transmitted. The estimate first made by Dr. Hirsch was, as already noted, 111 feet a second. More recent determinations give averages ranging from 97 feet, by Dr. Sohbleske, to 136 feet, Wittich'’s estimate for a nervoueimpnise excited by electricity. With a mechanical stimulus, he fonnd an average velocity of 124 feet. These figures, of conrse, are to be taken relatively. Therate varies in different individuals, and, douhtless, in tbe same individnal, with varying oonditions of liealth, temperatnre, and so on, the general average heing ahont that of a high wind, a race horse, or @ locomotive. Light excels it abont ten million times, and electricity more than fifteen million times.—Scientifie American, PxHoroonapHy aT THE Borrom oF THE SEA.— Nenmayer recently exhihited to the Berlin Gsographical Socisty a photographio apparatns designed for the determination of the temperatnre and of the cnrrents at great depths in the ocsan, The invention is composed of a copper box, hermetically sealed and fornished with an exterior appendix, made likea rudder. In the interior is a mercury thermometer and a compass, each enclosed in a glass receptacle, in which are admittsd traces of nitrogen gas. A small electric hattery completes the apparatus, When the latter is allowed to descend, attached to a sonnding line, the action of the enrrent on its rudder causee it to assnme a parallel direction, thue indicating the eet ot tbe flow by the’ rolative position of the compass, needle and rudder. The thermometer, of course, shows the surrounding temperature. In order to fix these indications, a piece of photographie paper is suitably disposed near the glase cases containing the instruments. Then at the proper time a ourrent of electricity is estahlished tbrongh the gas in the receptacles, cansing an intense violet light, capable of acting chemically upon the paper for a sufficient length of time to allow of the photography tbereon of tbe shadows of the compass needle and of the mercury colamn, Within three minutes, it “is said, the operation is complete, when tbe apparatns is hoieted and the paper removed. Anne Firxor has recently constrncted a new hattery, nsing a Spanish miners], which is prohably a kind of pyrites. The hattery is constant, and it has‘ heen fonnd that, after 18 months’ continuoue use, it operates as well as when first employed. ; ‘ Men of Science. Mr. Francis Galton, F. R.S., delivareda lectnrs at the Roys] Institntion, from which we gather the following interesting remarks: The datn for ths subject were the information fnroished in the replies tothe schedules sent ont by ths lectnror to 180 of the; leading scientific msn of the day, which wsre taken in total at abont 300. Of thess half were in age between 50 and 65; three-qnarters were English, and, aa compared to tho general ae. the proportion was 1 in 6,000. The inquiry wss then made into the causes which gave rise to these positions of eminence, Scientific discoveries were necessarily rere, and in some degree the conrse of individual mark was arace sgsinst time, Most remsrkahle, however, wss the almost persistent combination of remarkable energy of body with remarkable energy of mind. The returns made to the lecturer were neccssarily confidential, bnt he qnoted extracts to show illnstratione of each topic. Size of head was considered, and asa general role was larger than of ordinary gentlemen. Still, remarkahly many scientifio men had small heads, and the small heads were remarkable for activity. Health, again, was a marked featnre. Independence of spirit and tenacity of purpose were also most marked characteristios of men of science, and notably a large proportion were men of business as principals of large commercial or mereantile concerns. There were ten medical men also in the highest ranks of their profession, and 18 others in high posts not heing professorships. Tbe great incentive to science seemed to tho author to he innate taste, and in obaracter he regarded the scientific mind as anti-feminine. As to hereditary qnalities, that of health seemed most essentially dne to parentage; and on the psrental ‘side the infinence of qualitiss was apparently on the father’s side. The anthor appeared to consider that a combination of all essential qualities was necessary to the: prodnction of a man of mark, and that the laws of chances and alternativee came in to give actnality to the results. In regard to edncation, the general condition seemed to he that they were not tied down in their studies to particular snhjects, but were given to the investigation of many; and that they had heen in contact with persone of many ranks of society. There was a regret expressed of the time spent on classics in numerons instsnces and a general appreciation of, or desire for, a knowledge of mathematios; and admission in many cases of the yalne and infinence of home teachings. Finally, the lecturer advocated a national enlargement of moderate means of livelihood for those who desired to follow science, and the formation ofa sort of scientific priesthood, with a view to the ntilizstion of science to the general good. Tempenatuas of THE Eaatu.—In this country the earth’s temperatnre is constant at a depth of abont 50 feet, where the temperature is abont 50° Fah. The rate of increase of temperature isin our coal mines generally 19 ‘Fah. for every 60 feet of depth. It is questionshle, however, whetber after a great depth the rate of increase does not prove more rapid than before. Atthe deepest coal pit in England, namely, that at Rosebridge, near Wigan, where the shaft is now 2,376 feet deep, and is still descending, thsre is a ratio of heat increase agreed with thé ordinary rate down to a depth of 1,800 feet, after which it became considerahly more rapid. At the lowest point of the sinking the thermometer indicated 92° Fah.—The Engineer. Detection o¥ PaosHorus.—In testing bodies snpposed to have been poisoned by phosporns, the fatty matters present are an inconvenience. By Van Bastelaar’s method the liqnid is rapidly shaken.up with ether; the ethereal extract is evaporated, nnder protection from dnst. At the end of the operation a few drops of distilled water are added to hinder the aotion of the air npon the phosphorus. Under the water is deposited a liquid globnle composed of phosporns and fat. This is placedin a small tube, and agitated with strong ammonia at 21°; the ammonia is removed hy washing, first with very dilute sulphnric acid, and then with water. The phosphorus then remains, with all its pbysioal and chemical properties, Evortution or Gases From Mo.ren CastInoy.—-Ledehur thinks the evolution of gases is due to the tbree following canses: First, to those gases which have heen absorhed hy the molten metal within the furnace, and which are again evolved when the metal is cast, owing either to diminished pressnre, to a greater motion of the-iron, or to the iron again solidifying. Second, to a formation of gases prodnced hy chemical reaotions taking place when the molten metal comes in contact with -the air. Third, to a formation of gsses produced by cbemical process in consequence of the contact of the molten iron with the molds, Dexioats galyanometers ehould never be asin the case of the mariner’a compass, they are free to move in the direction of the lines of forces of the magnetic field in which they lie, otherwise they will qnickly lose their magnetism. TuALiiom in aminerals may be detected hy the spectroscope, when prosent in the proportion of 1 to 500,000. Paoors are given that ozone is soluble toa slight extent. . Kept.in the field of permanent magnets, nnless,MECHANICAL Procress Watches. Nelthropp, in his ‘Treatise on Watch-work,’” lInments that even educated men know bnt little cf the hsndy mschines they carry in their pookcts. Most people know a wntch when they seo it—this they cannot fsil to do; bnt as to distinguishing hetween a lever and a horizental, still less n ‘'verge,’”’ they are profonndly ignorant. Even in the matter of identifying a “eompsnsation”’ balance, the average henrer of a watch is deficient, as is proved hy the number of imitations abroad, which to the cursory observer present all the appearanco of the genuine norticle. Mr, Nelthropp says truly that the owner of a watch onght not to be éatisfied unless he knows enough abont ite working and construction to intelligently appreciate the really scicntifio workman—if he finds him— into wbose bands he commits his little mnchine for repair. Further than this, tbere are many minor things about watches that onght to be known by ordinary people, whioh will enable . 8 them to care for their timeksepers in an intelligent manner. For instance, more watches are spoilt by hasty and irregular winding-np than by most other canses, and a thonghtful ‘man ought to discover for himself that our author's advioe on the snbject is sonnd. A watch, he says, is mnch like a oliild, reqniring uniform treatment, ‘‘that is to say plainly, not over-indulged to-day, neglected to-morrow.” Windingnp shonld be performed regularly, with a steady and nnifurm motion, not moving hoth hands, and nearly as possible at the same honr daily. A watch should always he kept at the same temperatnre as nearly as possible. Left overnight on a stone mantelpiece,fit is snre to gain, or if the oil gets thickened, it msy stop, to be started again by the warmth of the pocket. The regulator is too often viewed as an appendage more to he looked at with wonder than to he nsed, while the persons who can explsin the theory of its action are few in tbe extreme, Yet the task of learning enongb ahont a watch to hecome capable of talking intelligently abont it, and exercising the control’ over a ‘jobber’? which that knowledge ie certain to give, is bunt slight, and it ought to he reckoned as hlameworthy to he iguorant abont one’s watch as to know nothing of the merits of one’s boote or clothing. Mr. Nelthropp gives to the nninitiated a few hints as to the pnrohsse of a watch which are worth reproducing. The case, he it gold or silver, should be correctly made and of fair thickness; the hinges close and smooth; the glass well fitted; the dial of clear, hright enamel; the seconds snnk, and the whole of good weight when held in the hand. When the dome is opened--for it is hetter that a watch-case should be so made, thongh more expensive—the brass-work should look well-finished, the edges smoothed off, the steel of a diamond-like polish, the jewels pale in color, but of a fine, clear luster; the action of the spiral spring shonld he even, when the watch is set going. Tur N, Y, Herald’s new press has attracted much attention among printers and engineers. Tbe dimensions of this machine are 4s follows: Length, 11 feet; width, 7 feet; length of cylinders, six feet; diameter of main cylinder, five feet; weight, 15 tons, It is furnished with four flys, which enable it to dispose of the sheets as fast as the press can print them. The main feature of this machine is that the roll of paper is tsken from the top of the cylinder and fixed on nprights at the hack of the prese,. connected with the cylinder hy means of a roller; the cutting of the paper is done after instead of before printing, the cutting cylinder being in the rear instead of the front of the machine, doing away with cams, grippers and tapes for carrying the cut sheets from one cylinder to another, and hy this means ohtaining a higher rate of speed. Compared with the Hoe ten-cylinder, the lahorsaving is immense, when we consider that it takes 15 men to work it effectively, while the Bnllock—the new press—requires the attendance of bnt three, and the saving in expense .} of running is averaged at $18,000 a year—almost the cost of the Bullock press. New MecuanrioaL Correa-Ovr.—A firm of Glasgow: ready-made, clothiers have jnst introduced a new machine for cutting out garments which will he the means of saving mnch labor. The ‘‘ band machine,”’ generally in use for cutting out ehirts and other articles is ill adapted for cutting out heavy garments, some more ex. peditions tool heing needed. In the Warth machine the scissors action is snhstitnted for the revolving blade. A piece of steel abont an inch and a-half long descends upon a slot, and thus cuts its way when propelled hy steam at the rate of 700 ‘‘ snips’’ a minnte, covering at the same time over two yards of matcrial. Paper raom Jure.—The Dundee Advertiser hss been:printed on paper made entirely from Calcutta jute enttings. The Advertiser's opinion of. the paper is as follows: ‘'It is an excellont paper, but not quite so bright in color as we could have wished, more resembling jhe color of paper sap pled to print secondclass books. We intend trying again to havea paroel of paper made of a good, bright color. The paper we have made is, however, ve1y tough, splendid in every particnlar for the newspaper trade.” Testing Armor Plates. In England, hefore the plates are sent to the deckyard, one or more are ohossn at rsndom hy @ government official to he tested. The plstes arc fastened to a targst srected at one end of the ship, snd shots are fired atthem from guns of prescribed caliber, in a battery at the other ent, the men being protected from the splinters of the shot by a casement. If ths plats does not stand the test satisfsctorily, the lot from which it was selected is rejected. This system ef tests ssonres as good an article as it is possihle to make. During the first few years of the msnninctnre it was fonnd thnt the plates were often split and erscked by the shot, in the neighhorhood of the holes which had to he hored through them for the screwa or holts hy which they are attached to the targets. It wss thue sssnmed that these hcles were necessarily a sonrce of great weakness, ond many schemes were proposed for connecting plates with the ship’s side in ways hy which this important defeot might he avoided. One was tbat an iron frame should be attached to the ship and the plate dropped into it, the edges of the frame heing afterward beaten over to secnre the platein its place. The necessity for anything of this kind has*been obviated hy the reat Improvements which have been effected in the qnality of the armor; the metal now used is 80 tenacions that it is soarcely any weaker in the neighhorhood of a bolt holo than in any other place. The snperiority of the armor of tbe present day over that made 10 years ago was fnlly exemplified in the recent experiments on the turret of the “'Glatton.” A hole was pnnched throngh one of her 14-inch plates by the shot, bnt there was no other damage done to the plate than the mere penetration. Under similar cirenmstances in the case of plates: experimented npon some years ago, there would he seen large cracks radiating from the shot hole, producing a complete separation of the plate as far asthe nearest holt holes, and in many cases the armor plate wonld have heen broken in two or three pieces. A Compound Locomotive. An ingenions member of the Manchester Soientific and Mechanioal Society proposes to apply the componnd principle to locomotives. This is how he sets about it, ssys the English Mechanic: He wonld nse eteam of 250 ibs. on the square inch to work the small cylindsr, and expand this eteam into a supplementary boiler hearing n pressnre of 6(or 65 ibs. to the square inch, so as to have a surface of effeotive pressure of 180 ibs. or 190 ibs. in the small cylinder, or abont 60 or 65 ibs. in the lsrger one. The principal alterations proposed are in the boiler. Ic adapting his plan to a locomotive of the medinm size, he would make the boiler two feet longer than at present, and divide it into two distinct parts, the part containing the furnace or fire box to be two feet shorter than at present, so as to have the supplementary hoiler fonr feet longer, hoth being equal in diameter, and equal in nninber, size and position of tuhes, the two parta of the hoiler heing firmly holted together, and so arranged that the tubes of one are in a line with the other, so the hot air and flame may pass freely throngh from one to the other. An important advantage claimed hy tbe plan is that the driver of the locomotive will he enabled to start his engine with the fnll power of steam in hoth cylinders at once, which he oould not do, if compounded in the nsnal way. Although this” plan will require extra ontlay, there will be a considerable saving in fuel, which, with other advantages, it is claimed, will more than compensate for the extra cost. We are not surprised to hear that discussion followed the reading of the paper, in which the feasihility of the’ plan wae generally condemned. Ultimately, however, the disenssion was adjonrned, in order that the inventor might give fnrtber information on the subject. Liqueryinae Gases.—M, Mellens ssturates charcoal with an amount-of chlorine whose weight will be eqnal to that of the charcoal, places it in one limb of a V-shaped tahe, sealing both extremities thereof, and applies boiling watsr to this limb, cansing the volatilized chlorine to rise in the other limh, when, nnder the pressure prodnced, it may be liqnefied by dipping the latter limh in a freezing mixturd. He liqnefies ammoniz, sulphnrons,.hydro-snl-phuric and hydro-hromic acids, chloride of ethyl and cyanogen in the same manner. Horzow Bars ror Fugnaors.—The chie features of novelty inthis invention are: Forming the hollow hars of cast iron having two or more longitndinal water passages; providing the ends of the passsges with removable screwIngs or other stoppers to facilitate cleaning; a, flplahSaabered hearing-pieces to snpply water to bars; placing the donble-chambered bearing-piece in the middle of long bars; snpplying the feed-water in some cases from a snrface condenser. Improvep Fisu-Grapriine Spean.—The spesr books are jointed together and provided with springs, which are bent when the hooks are opened, and held by the toggle joint nntil the latter is sprung, and then close them with snfiicient force to secure the fish. Tue Preece block system of electric railway signalizing is working on the principle that the trains are tobe kept acertain nnvarying distance apart. No train can sdvance nntil the signal is given tbat the line for the spscific distance ahead is ahsolntely clear.

July 25, 1874-] 5] MINING AND SCIENTIFIC PRESS. SciENTIFIC (PRocREss. Celocity of Nervous Impulses, However slow the rate of nervous movomsent mey be, as compared with the velocity of light or tbe atill feeter anotion of electricity, it is neverthelees so rapid that until qnite recently it was thonght to immeusurable, within the limited range in which onr observation of it is possible. The most widely aeparated points in the course of any nerve allow hut a few feet of difference at hoat for timing the periods of sen. sation or volition; and the nervous impulse travels so qnickly that snch small distances wonld seem to he wholly annihilated, To our concionsness a prick on the groat toe is discovored ns promptly as one on the cheek; and it is only by the intervention ot the most delicate and ingenions of meohanical contrivances that the difference in time is made apparent. In all the early experiments on motor nerves, the leg of n frog bad heen nsed. In 1867, Baxt and Helmholtz applied the test to man, nsing an improvement of the myogrsphicon suggested by Dn Boie Raymond. Tbe resnit gave the rate of condnetion for the motor nerves of man, corrosponding to that already obtained by Hirsch forthe sensory nerves, A very oareful seriea of experiments by the same observers, in the summer of 1869, showsd a mean rapidity for the motor nerves in man very mnch greater, or about 254 feet a second. The measnrement of the rate at which the nervous impnise travels hrainward necessarily involves a process very different from any employed inthe stndy of motor nerves. The problem wss first attacked by the Swiss astronomer, Dr, Hirsch, soon after Helmholtz took np tbe other branoh of the investigation, and his solution of it was as ingenions as it was suoeessfnl. It involved the measnrement, with the delicate ohronometric instruments employed by astronomers, of tbe difference in time hetween the appreciation of impressions made at a distance from the hrain, say on the great toe, and others nearer, as on the cheek. Ronghly deseribed, the plan adopted wae substantially this: The ohserver sat with his finger on a signal key, with which he announced the perception of an electrio shock as soon as possible after feeling it, thns closing an electric circnit which had heen broken by theshock. The min. nte interval between the breaking and closing of the cirenit measured the time taken hy the trsnamission of tbe shock to the brain, thetime reqnired for the perception of the sensation, time for willing the movementof the signal key, time for the transmission of this volition to the proper mnscles, time for the contraction of the musoles, and finally the time lost in tho physical process of eignaling. Obvionsly all these parts, except the first, must he substantially the same in all experiments by the eame person, nsing the saine finger for making the signal. Any difference in the whole time must therefore be owing to the greatsr or smaller distance of the partivnlar point of impression from the brain. This difference being measured with tolerable exactness, it is possible to calcnlate pretty closely the rate at which the nervons impnise is transmitted. The estimate first made by Dr. Hirsch was, as already noted, 111 feet a second. More recent determinations give averages ranging from 97 feet, by Dr. Sohbleske, to 136 feet, Wittich'’s estimate for a nervoueimpnise excited by electricity. With a mechanical stimulus, he fonnd an average velocity of 124 feet. These figures, of conrse, are to be taken relatively. Therate varies in different individuals, and, douhtless, in tbe same individnal, with varying oonditions of liealth, temperatnre, and so on, the general average heing ahont that of a high wind, a race horse, or @ locomotive. Light excels it abont ten million times, and electricity more than fifteen million times.—Scientifie American, PxHoroonapHy aT THE Borrom oF THE SEA.— Nenmayer recently exhihited to the Berlin Gsographical Socisty a photographio apparatns designed for the determination of the temperatnre and of the cnrrents at great depths in the ocsan, The invention is composed of a copper box, hermetically sealed and fornished with an exterior appendix, made likea rudder. In the interior is a mercury thermometer and a compass, each enclosed in a glass receptacle, in which are admittsd traces of nitrogen gas. A small electric hattery completes the apparatus, When the latter is allowed to descend, attached to a sonnding line, the action of the enrrent on its rudder causee it to assnme a parallel direction, thue indicating the eet ot tbe flow by the’ rolative position of the compass, needle and rudder. The thermometer, of course, shows the surrounding temperature. In order to fix these indications, a piece of photographie paper is suitably disposed near the glase cases containing the instruments. Then at the proper time a ourrent of electricity is estahlished tbrongh the gas in the receptacles, cansing an intense violet light, capable of acting chemically upon the paper for a sufficient length of time to allow of the photography tbereon of tbe shadows of the compass needle and of the mercury colamn, Within three minutes, it “is said, the operation is complete, when tbe apparatns is hoieted and the paper removed. Anne Firxor has recently constrncted a new hattery, nsing a Spanish miners], which is prohably a kind of pyrites. The hattery is constant, and it has‘ heen fonnd that, after 18 months’ continuoue use, it operates as well as when first employed. ; ‘ Men of Science. Mr. Francis Galton, F. R.S., delivareda lectnrs at the Roys] Institntion, from which we gather the following interesting remarks: The datn for ths subject were the information fnroished in the replies tothe schedules sent ont by ths lectnror to 180 of the; leading scientific msn of the day, which wsre taken in total at abont 300. Of thess half were in age between 50 and 65; three-qnarters were English, and, aa compared to tho general ae. the proportion was 1 in 6,000. The inquiry wss then made into the causes which gave rise to these positions of eminence, Scientific discoveries were necessarily rere, and in some degree the conrse of individual mark was arace sgsinst time, Most remsrkahle, however, wss the almost persistent combination of remarkable energy of body with remarkable energy of mind. The returns made to the lecturer were neccssarily confidential, bnt he qnoted extracts to show illnstratione of each topic. Size of head was considered, and asa general role was larger than of ordinary gentlemen. Still, remarkahly many scientifio men had small heads, and the small heads were remarkable for activity. Health, again, was a marked featnre. Independence of spirit and tenacity of purpose were also most marked characteristios of men of science, and notably a large proportion were men of business as principals of large commercial or mereantile concerns. There were ten medical men also in the highest ranks of their profession, and 18 others in high posts not heing professorships. Tbe great incentive to science seemed to tho author to he innate taste, and in obaracter he regarded the scientific mind as anti-feminine. As to hereditary qnalities, that of health seemed most essentially dne to parentage; and on the psrental ‘side the infinence of qualitiss was apparently on the father’s side. The anthor appeared to consider that a combination of all essential qualities was necessary to the: prodnction of a man of mark, and that the laws of chances and alternativee came in to give actnality to the results. In regard to edncation, the general condition seemed to he that they were not tied down in their studies to particular snhjects, but were given to the investigation of many; and that they had heen in contact with persone of many ranks of society. There was a regret expressed of the time spent on classics in numerons instsnces and a general appreciation of, or desire for, a knowledge of mathematios; and admission in many cases of the yalne and infinence of home teachings. Finally, the lecturer advocated a national enlargement of moderate means of livelihood for those who desired to follow science, and the formation ofa sort of scientific priesthood, with a view to the ntilizstion of science to the general good. Tempenatuas of THE Eaatu.—In this country the earth’s temperatnre is constant at a depth of abont 50 feet, where the temperature is abont 50° Fah. The rate of increase of temperature isin our coal mines generally 19 ‘Fah. for every 60 feet of depth. It is questionshle, however, whetber after a great depth the rate of increase does not prove more rapid than before. Atthe deepest coal pit in England, namely, that at Rosebridge, near Wigan, where the shaft is now 2,376 feet deep, and is still descending, thsre is a ratio of heat increase agreed with thé ordinary rate down to a depth of 1,800 feet, after which it became considerahly more rapid. At the lowest point of the sinking the thermometer indicated 92° Fah.—The Engineer. Detection o¥ PaosHorus.—In testing bodies snpposed to have been poisoned by phosporns, the fatty matters present are an inconvenience. By Van Bastelaar’s method the liqnid is rapidly shaken.up with ether; the ethereal extract is evaporated, nnder protection from dnst. At the end of the operation a few drops of distilled water are added to hinder the aotion of the air npon the phosphorus. Under the water is deposited a liquid globnle composed of phosporns and fat. This is placedin a small tube, and agitated with strong ammonia at 21°; the ammonia is removed hy washing, first with very dilute sulphnric acid, and then with water. The phosphorus then remains, with all its pbysioal and chemical properties, Evortution or Gases From Mo.ren CastInoy.—-Ledehur thinks the evolution of gases is due to the tbree following canses: First, to those gases which have heen absorhed hy the molten metal within the furnace, and which are again evolved when the metal is cast, owing either to diminished pressnre, to a greater motion of the-iron, or to the iron again solidifying. Second, to a formation of gases prodnced hy chemical reaotions taking place when the molten metal comes in contact with -the air. Third, to a formation of gsses produced by cbemical process in consequence of the contact of the molten iron with the molds, Dexioats galyanometers ehould never be asin the case of the mariner’a compass, they are free to move in the direction of the lines of forces of the magnetic field in which they lie, otherwise they will qnickly lose their magnetism. TuALiiom in aminerals may be detected hy the spectroscope, when prosent in the proportion of 1 to 500,000. Paoors are given that ozone is soluble toa slight extent. . Kept.in the field of permanent magnets, nnless,MECHANICAL Procress Watches. Nelthropp, in his ‘Treatise on Watch-work,’” lInments that even educated men know bnt little cf the hsndy mschines they carry in their

pookcts. Most people know a wntch when they seo it—this they cannot fsil to do; bnt as to distinguishing hetween a lever and a horizental, still less n ‘'verge,’”’ they are profonndly ignorant. Even in the matter of identifying a “eompsnsation”’ balance, the average henrer of a watch is deficient, as is proved hy the number of imitations abroad, which to the cursory observer present all the appearanco of the genuine norticle. Mr, Nelthropp says truly that the owner of a watch onght not to be éatisfied unless he knows enough abont ite working and construction to intelligently appreciate the really scicntifio workman—if he finds him— into wbose bands he commits his little mnchine for repair. Further than this, tbere are many minor things about watches that onght to be known by ordinary people, whioh will enable . 8 them to care for their timeksepers in an intelligent manner. For instance, more watches are spoilt by hasty and irregular winding-np than by most other canses, and a thonghtful ‘man ought to discover for himself that our author's advioe on the snbject is sonnd. A watch, he says, is mnch like a oliild, reqniring uniform treatment, ‘‘that is to say plainly, not over-indulged to-day, neglected to-morrow.” Windingnp shonld be performed regularly, with a steady and nnifurm motion, not moving hoth hands, and nearly as possible at the same honr daily. A watch should always he kept at the same temperatnre as nearly as possible. Left overnight on a stone mantelpiece,fit is snre to gain, or if the oil gets thickened, it msy stop, to be started again by the warmth of the pocket. The regulator is too often viewed as an appendage more to he looked at with wonder than to he nsed, while the persons who can explsin the theory of its action are few in tbe extreme, Yet the task of learning enongb ahont a watch to hecome capable of talking intelligently abont it, and exercising the control’ over a ‘jobber’? which that knowledge ie certain to give, is bunt slight, and it ought to he reckoned as hlameworthy to he iguorant abont one’s watch as to know nothing of the merits of one’s boote or clothing. Mr. Nelthropp gives to the nninitiated a few hints as to the pnrohsse of a watch which are worth reproducing. The case, he it gold or silver, should be correctly made and of fair thickness; the hinges close and smooth; the glass well fitted; the dial of clear, hright enamel; the seconds snnk, and the whole of good weight when held in the hand. When the dome is opened--for it is hetter that a watch-case should be so made, thongh more expensive—the brass-work should look well-finished, the edges smoothed off, the steel of a diamond-like polish, the jewels pale in color, but of a fine, clear luster; the action of the spiral spring shonld he even, when the watch is set going. Tur N, Y, Herald’s new press has attracted much attention among printers and engineers. Tbe dimensions of this machine are 4s follows: Length, 11 feet; width, 7 feet; length of cylinders, six feet; diameter of main cylinder, five feet; weight, 15 tons, It is furnished with four flys, which enable it to dispose of the sheets as fast as the press can print them. The main feature of this machine is that the roll of paper is tsken from the top of the cylinder and fixed on nprights at the hack of the prese,. connected with the cylinder hy means of a roller; the cutting of the paper is done after instead of before printing, the cutting cylinder being in the rear instead of the front of the machine, doing away with cams, grippers and tapes for carrying the cut sheets from one cylinder to another, and hy this means ohtaining a higher rate of speed. Compared with the Hoe ten-cylinder, the lahorsaving is immense, when we consider that it takes 15 men to work it effectively, while the Bnllock—the new press—requires the attendance of bnt three, and the saving in expense .} of running is averaged at $18,000 a year—almost the cost of the Bullock press. New MecuanrioaL Correa-Ovr.—A firm of Glasgow: ready-made, clothiers have jnst introduced a new machine for cutting out garments which will he the means of saving mnch labor. The ‘‘ band machine,”’ generally in use for cutting out ehirts and other articles is ill adapted for cutting out heavy garments, some more ex. peditions tool heing needed. In the Warth machine the scissors action is snhstitnted for the revolving blade. A piece of steel abont an inch and a-half long descends upon a slot, and thus cuts its way when propelled hy steam at the rate of 700 ‘‘ snips’’ a minnte, covering at the same time over two yards of matcrial. Paper raom Jure.—The Dundee Advertiser hss been:printed on paper made entirely from Calcutta jute enttings. The Advertiser's opinion of. the paper is as follows: ‘'It is an excellont paper, but not quite so bright in color as we could have wished, more resembling jhe color of paper sap pled to print secondclass books. We intend trying again to havea paroel of paper made of a good, bright color. The paper we have made is, however, ve1y tough, splendid in every particnlar for the newspaper trade.” Testing Armor Plates. In England, hefore the plates are sent to the deckyard, one or more are ohossn at rsndom hy @ government official to he tested. The plstes arc fastened to a targst srected at one end of the ship, snd shots are fired atthem from guns of prescribed caliber, in a battery at the other ent, the men being protected from the splinters of the shot by a casement. If ths plats does not stand the test satisfsctorily, the lot from which it was selected is rejected. This system ef tests ssonres as good an article as it is possihle to make. During the first few years of the msnninctnre it was fonnd thnt the plates were often split and erscked by the shot, in the neighhorhood of the holes which had to he hored through them for the screwa or holts hy which they are attached to the targets. It wss thue sssnmed that these hcles were necessarily a sonrce of great weakness, ond many schemes were proposed for connecting plates with the ship’s side in ways hy which this important defeot might he avoided. One was tbat an iron frame should be attached to the ship and the plate dropped into it, the edges of the frame heing afterward beaten over to secnre the platein its place. The necessity for anything of this kind has*been obviated hy the reat Improvements which have been effected in the qnality of the armor; the metal now used is 80 tenacions that it is soarcely any weaker in the neighhorhood of a bolt holo than in any other place. The snperiority of the armor of tbe present day over that made 10 years ago was fnlly exemplified in the recent experiments on the turret of the “'Glatton.” A hole was pnnched throngh one of her 14-inch plates by the shot, bnt there was no other damage done to the plate than the mere penetration. Under similar cirenmstances in the case of plates: experimented npon some years ago, there would he seen large cracks radiating from the shot hole, producing a complete separation of the plate as far asthe nearest holt holes, and in many cases the armor plate wonld have heen broken in two or three pieces. A Compound Locomotive. An ingenions member of the Manchester Soientific and Mechanioal Society proposes to apply the componnd principle to locomotives. This is how he sets about it, ssys the English Mechanic: He wonld nse eteam of 250 ibs. on the square inch to work the small cylindsr, and expand this eteam into a supplementary boiler hearing n pressnre of 6(or 65 ibs. to the square inch, so as to have a surface of effeotive pressure of 180 ibs. or 190 ibs. in the small cylinder, or abont 60 or 65 ibs. in the lsrger one. The principal alterations proposed are in the boiler. Ic adapting his plan to a locomotive of the medinm size, he would make the boiler two feet longer than at present, and divide it into two distinct parts, the part containing the furnace or fire box to be two feet shorter than at present, so as to have the supplementary hoiler fonr feet longer, hoth being equal in diameter, and equal in nninber, size and position of tuhes, the two parta of the hoiler heing firmly holted together, and so arranged that the tubes of one are in a line with the other, so the hot air and flame may pass freely throngh from one to the other. An important advantage claimed hy tbe plan is that the driver of the locomotive will he enabled to start his engine with the fnll power of steam in hoth cylinders at once, which he oould not do, if compounded in the nsnal way. Although this” plan will require extra ontlay, there will be a considerable saving in fuel, which, with other advantages, it is claimed, will more than compensate for the extra cost. We are not surprised to hear that discussion followed the reading of the paper, in which the feasihility of the’ plan wae generally condemned. Ultimately, however, the disenssion was adjonrned, in order that the inventor might give fnrtber information on the subject. Liqueryinae Gases.—M, Mellens ssturates charcoal with an amount-of chlorine whose weight will be eqnal to that of the charcoal, places it in one limb of a V-shaped tahe, sealing both extremities thereof, and applies boiling watsr to this limb, cansing the volatilized chlorine to rise in the other limh, when, nnder the pressure prodnced, it may be liqnefied by dipping the latter limh in a freezing mixturd. He liqnefies ammoniz, sulphnrons,.hydro-snl-phuric and hydro-hromic acids, chloride of ethyl and cyanogen in the same manner. Horzow Bars ror Fugnaors.—The chie features of novelty inthis invention are: Forming the hollow hars of cast iron having two or more longitndinal water passages; providing the ends of the passsges with removable screwIngs or other stoppers to facilitate cleaning; a, flplahSaabered hearing-pieces to snpply water to bars; placing the donble-chambered bearing-piece in the middle of long bars; snpplying the feed-water in some cases from a snrface condenser. Improvep Fisu-Grapriine Spean.—The spesr books are jointed together and provided with springs, which are bent when the hooks are opened, and held by the toggle joint nntil the latter is sprung, and then close them with snfiicient force to secure the fish. Tue Preece block system of electric railway signalizing is working on the principle that the trains are tobe kept acertain nnvarying distance apart. No train can sdvance nntil the signal is given tbat the line for the spscific distance ahead is ahsolntely clear.