Volume 24 (1872) (424 pages)

February 10, 1872.]} SCIENTIFIC PRESs: 83 NM ECHANICAL Procress Friction Gearing vs. Belts and Cog Wheels. Experiments in the uso of friction gearing—that is, of pulleys transmitting power, by direct frictional contact between the sinooth faces of the driving and the driven pulley instead of hy means of belts or y cogs meshing into each other—have been very freqnontly made, and in mauy cases with remarkable snecess. So cmphatic, are the recommendations of this method of gearing, giveu by men who have tried or witnessed its operation, that it is somewhat a matter of surprise that it has not heeu more generally adopted. It is claimed by many such persons to be equally well ndapted to the propelling of gang, umnlay or cirenlar saws, mill burrs, or in fact almost any description of machinory, and to the transmission of any amonnt of power with tle same or cyen greater usoful effect than when belts or cog wheols aro omployed. In the vicinity of Clinton, Towa, some years ago, friction pulleys wero introduced in a saw-mill with such complete success in point of oconoinmy aud convenience, that they soon hecamo an established institution thronghont that entire rsgion, superceding helts altogether, the latter bsing in eomo instances thrown ont at a heavy expense to give placo to the now order of things. Tho pulleye usod in this case were built of soft and tough wood, strongly put together by thoir segmente in such a manner as to presont the least possihlo end grain of wood to the eurface. They were placed on the main shaft, to which the powsr was applied hy tho engino crank or taken from the water wheel, as tho case might he, in the ordinary manner. The faces of the pulleys were cither parallel to the shaft or beveled at any angle required, according to the direction of the counter shafts to which the power was communicated. The segments of tho pulleys were glued or painted together and their facos turned off perfectly true. It was found that thsy required about one-third more width of face than would he necsssary if belts were used. In one case, two gangs were run, each with a friction pulley three feet in diameter and having 24 inches face. For a mulay or rotary saw mill, a pulley of from 12 to 16 inches face was found sufticieut. A friction pulley, tsn inches in diameter with six-inch face, was descrihed as giving more useful effect and heating the hoxss less than when the same pulley was used with a fonr-inch helt. From the numerous experiments made, the conclusion was reached that a pulley of 20 inches faco would successfully transmit 50 horee power without undue wearing or heating. The epecial advantages claimsd for this method were the saving of the expense of providing belts and loose pulleys and keeping them in repair, Tho mills were so arranged that each machino was run with its own counter shaft, geared either to tho engine shaft or to ono of the main counter shafts so that each workman could control the operation of his own machine indopendently of tho others, and with no throwing off or putting ouhelts. ‘Ths pulleys on the counter shafts were of iron and very strong, each having the sams face, of course, as the driving pulley, hut being of any desired diameter, according to the motion to be obtained. By msane of a movable bearing operated hy a lever, the iron pulley was readily brought in contact with its driver, the motion necessary for this purpose being less than one-eighth of an inch. The statement that, for the proper working and durability of a friction pulley, it ehould he so made as to present as little snd grain as possihle to the surface, is emphatically disputsd by experienced workmen, who claim that the precise opposite to this is the true method, and that the pulley should he so made as to offer the end grain to the contact of the other pulley to the ntmost practicable extsnt. To accomplish this purposs, the pulley is made of segments of wood, cut ont of a plank iu the shaps of a fan, the grain run. ning parallel with one side of the fan, and the end grain being represented in a slightly oblique manner at the outer or circular edge. These segments are put togsther strongly, and so arranged that the grain shall not run in the same direction iu two pieces in contact with each other, but cross in much the same manner as the furrows iu the upper and under millstone. The object ofthis is to prevent the face of the pulleys from too grsat tendency to wear in any given direction. The rim of the whesl, ag it may he ealled for covenience, is hnilt up hy laying ths first tier of segments, making a eomplete wheel of the thickness of the plank, flat upon the bench, and placing tho other layers succsesivoly upon this, hreaking joiuts and crossing the grain as already indicated. The layors are vory strongly scenred to each other with wrought nails, heside which glue or whito lead is laid on hetween them. ‘The rim hsing complete, mortises or guins are made to receive the pads of the spider at the end of the radial arms, these gains heing somewhat larger than the pads, and ths space thus given boing billed hy ths insertion of keys, one on each side of ths pad, entering from opposits directionsand overlupping cach other, the whole leugth of the pad, Bolts are also inserted, pass: ing through tho pad ina radial direction, with countersinking on the face of the pulley aud a nut ou the inner ond. ‘Tho countorsink is afterward filled hy plugging, over tho head of the holt. The conflict of testimony iu regard to tho comparative eflieiency of the pulloys iu which tho ond grain is prosented to the enrfaco and thoso in which it runs lengthwise with tho circumference is somewhat surprising, as the point is easily subjected to a practical tsst. Most mechanics will take ground without hesitation in favor of end grain, as less liahle to yicld and curl or ‘*hroom” up, whon subjected to powerful aud constautpressure.—Leffel's Mechanical News. Notzine Iron.—Nothing is moro noticeahle than the various chauges which have been made in the method of finishing iron in rolling mills during the last five years. A few years ago our mills furnished all their irou in hars, sheets, rails, or such shapes as were demanded hy soparate estahlishments. Of late the iron manufacturers have added to their mille other hranchee of iron working, which can he dons hy thsw at much less cost than hy those who were simply purchasers from the mills, and who lost considerahle in the ehape of ‘‘ecraps” in working up the iron jn various articles. Said ‘‘scrap”’ was necesearily brought hack to the millagain and sold at a greatly reduced rats. Thus it will be seen that the rolling mill that finishes ths iron direct into nuts, bolts, horse shoes, washers, railroad chairs, etc., possessea a great advantage in making these articles, which are heginning to hs viewed as a part of the rolling mill husiness, Galvauizing eheet iron, making gas pipe, strap hangings, and many other things are now made by rolling mills with more profit to themselves and the puhlic, tlian by the old method. Properly managed, the finishing of iron into these and other articles cannot fail to prove profitahle to the manufacturer. Trustine Corron Gins.—A series of interesting experiments have heen proposed at Manchester, England, for the purpose of testing the merite of the various cotton gins, for working different kinds of cotton, or ssparating tbe fihre from the seed. The points to be dstermined for each gin, and in respect to each variety of cotton are:—First—the speed of working, as tested by tho time in which a given quautity of ssed cotton can be ginned; second— The facility of working as tested by the quantity of power consumed in the operation; third—The quality of working, as tested hy the conditiou of the ginned fihre and the soparated seed respectively. In order to make the experiment as conclusiveae possihle a eeries of very ingsuious regulations have been framed to exclude the possihility of any kind of error or deception. Three principal classes of gins have hesn entered for competition namely, the roller gins, knife and roller gins, and eaw gins. Such tssts might be made with many other kinds of machinery, much to the advantage of the public and to all reully meritorious inventors. Aurating WatTrrR.—A contrivance of recent date for aerating water produced from the condensation of steam, comprises a tank with a eeries of porous or open work partitions, some containg wool and felt, with the spaces hetween filled with coke and chalk. The last compartment has a psrforated hottom, through which air is forced and rises in minute hubbles. . From an interesting article iu a recent issue of London Zimes, we lsarn that steam cultivating machinery is coming into very general use in England. One large firm have besn ssnding ont from eight to ten plowing sngines per week, most of which are for uee in districts where they can be hired by several different farmere, 4 ; BCIENTiFIC Progress, The Permanent Gases. It is a generally received opinion that all gases are mere vapors of liquids that hoil nt very low tempsratures. Thns, whils watsr hoils at 212 , commou cther hoils at 96°, and sulphurous acid at U. Consequently, while water is always a solid or a liquid, in all parts of the earth, ethsr would he a psrmuauent gas in any place where the highest tropical temperature provailed, and snlphurous acid is always n gas except in ths eold of the polar regious. yon merenry, when exposed to a temperature euilicioutly high, hecomes transparent gas, and carhonic acid gus, when exposed to a temperature sutliciently low, becomes first a ysllowish liquid, aud then a beautifnl, snow-white solid. ‘The only ditfereuce, then, hetwcon commou snow and carhonie acid snow is that ths one is much colder than the other, while, on the other hand, the only differouce betweon carhonie acid gas and mercury gas is that tho one requires a higher temperature for its existouce thau the other. There are cortain gasce, however, which no degree of cold yst reached has reduced to the liqnid, far lese to the solid form. Prominent amongst these are oxygen and hydrogen—the gases that, comhined, form water. But after it had hesn ohserved that inteuse cold tended to reduce all gasee and vapors to the liquid form, theee gases were cooled with freszing mixtures; etill they remained in the gaseous state, although msrcury became solid, and alcohol, unless very pure, hecame thick aud pasty. After a time, a still more powerful freezing mixture (liquefied laughing-gas) was discovered, and hy a powerful steel pump was forced into a large iron receiver until it hecame liquetied with the pressure. When a little of this liquid was poured into the air, it evaporated, and produced the greatsst degrss of cold ever ohserved— 257° Fuh, Even then, oxygen and hydrogen did not liquefy, hut maintained their condition as clear and beautiful gases. But cold aloue was not the only agent hrought to hear on these gases. They were eubjected to immense pressurs, far exceeding anything with which ws are familiar in ordinary life. Nattersr constructed a eeries of very finely made steel pumps. With one of thsse, he condensed one of the gases into a strong vessel until it occupied but the three-hundreth part of its original hulk. ‘Then, with a etill more powerful pump, hs condensed this already deueo gas, so ae to reduee it still further. It will readily he seen that, hy employing gae in a condsnsed state, it was much easier to force it through the valves of the second pump than if gas at the ordinary pressure had heen used. In this way, hy working with gas gradually increasing in deneity, he finally ohtained a pressure of 3,000 atmospheres, or 22% tons to theiuch. If we have no idea of a temperature of 257° helow zero, ueither can we fully grasp the enormous pressure expressed hy the figures 2224 tons per squareinch. Most solid suhstances would he crushed to powder under snch a pressure as this. And yet to this wonderful pressure did Natterer subject oxygen and hydrogsu. But even that temperature and pressure madezno impression on them, at least so faras change of form is concerned. But thatwhich Natterer, aided by all the resources of modern science, failed to do, chemical affinity does instantly and perfectly. Mix the gases iu proper proportions and hring the smallest flame into contact with them, so as to produce ignition, and they will instantly rush togsther with a loud report, combine and form a perfect liquid, water. It is perfectly obvious that the elementary atoms of this new liquid water, must he hsld together hy a force euflicisut to overcome their expansive force, We have seen what this expansive force is capahle of resisting, and consequently we can form 2 comparative sstimate of the power of chemical affinity.—Condensed from Phin’s Chemical History. Votoanio Ervptions.—Archdeacon Pratt, by discussing the amount of prscession in a glohe with a molten nucleus, finds conclusive evidsnce of Sir Wm. Thompson’s opinion that the earth is solid, and that, therefore, volcauic eruptions are attributable to some other cause than the one popularly assigned. His view is confirmed by numerous recent observations, which indicate that the increase of tsmperature, helow the sarth’s eurface, soon reaches a limit. THe Sanp Buast.—The uniform success which has attended the use of the sand hlast has sufficiently proved its reliahility, and the numerous purposes to which it can he applied, promiss to rendsr it ons of the most useful iuventions that have heeu of late hrought into public notice. By simple moditiestions it can ho mads to snpercede the present slow and costly process for shaping grauits and othsr hard stones, for rock drilling aud for polishing castings, or grindiug aud engraving glass. The cost of working it iee#trsmely small and there ueed he no loss of ths sand employed, ae it can be constantly restored to the feeding hopper, together with the particles driven from the material. The action of the sand upon a hard surface appears to he due to the work performed by cach angular particle that strikes, and which in striking carries away with ita particle, of course far smaller thau itselt, sud the reason why the softer materials resist the wearing action, is due to tho elasticity which repets the particles. Asa proot of this, it may he mentionod that while perforated shield plates of lace, golatine, or ruhher bear a prolonged exposure to tho sand, unharmed, stencils of thin sheet steel or hrass curl up, and are destroyed.— Engineering. Tue Pwneumatio Sewaoz Systemw in which air is the power employed for cleauing the sowers of matter otherwise likely to accumulate, is discussed with much interest hy eome of our foreign exchanges. The plan is to divide a city into complexes and suh-complexes, a suh-complsx coneisting of ahout 200 houses, and a complex comprising all the sub-complexes within a radius of 2,500 feet. Exch complex has a large air-tight cast iron reservoir, and each suh-complex a small one connecting with the muin reservoir and with the houses, hy means of pipes provided with valvss and cocke, hy which all circulation of air may be prevented. The air insido is exhausted hy means of a largs air pump driven in connsction with the main ressrvoir hy means of a powerful steam engine, and then the outer air, pressiug upon the contents of the pipes, forces them into the reservoirs. By this means the pipes may all be cleared in lsss than five minutes, their contsnts first passing into the eub-rsservoirs, and then into the main one. ‘This simple and eminently eanitary system has for some time past hesn in successful operation in the city of Prague, Bohemia, and is heing introduced into other European cities. —Lz. Accuracy or TELEGRAPHIC ESTIMATES OF Loneirupes.—The great accuracy with which diffsreuces of longitude can he ascertained by the magnetic telegraph is illnstrated hy soms of the determinations for the United States Coast Survey. Where the longitudes were estimated hy four differsnt circuits, the greatest difference between any two determinations was twentyeight thousandths of a second, equivalent to about thirty feet, the mean error being lsss than one millionth of the distance hetween the two objective points, which, in some cases, as in that hstwesn Cambridge and San Francisco, was 3,080 miles. New Usz ror Expcrriciry.—Electricity has achieved a newtriumph. Already employed to restors vigor and nimbleness to the gouty limhs of decrepit bons vivants, the recent discoveries of Dr. Bernier, a French physician, show electricity to he an efficient remedy for the evil effects of excessive drinking on the human nose. The doctor mantains that, hy the application of an electric current to noses even of the most Bacchanalian hue, the flesh may he made ‘“‘to come again asthe flesh of a little child ;” and he supports his assertion hy a case performed on a female patient of his own, a woman of high rank.—Sci. Am. Tue Foes Puants or Canapa.—Dr. J. W. Dawson, of the Geological Survey of Canada, has just puhlished hie report ou the fossil land plants of the Devonian and Uppsr Silurian formations of Canada. In this report, he has catalogued or described more than 120 species of land plants found in formations older than the carhoniferousin Canada, thus placing the knowledge of this old flora in advance of that of any other portion of the world. A New Mops or Forinne Perrror CrysTaLs.—Prof. Schultzs states that by tbe use of gelatinizing liquid as a solvent, erystals of various substances may be ohtained completely formed. In proof, a number of fine crystals of sugar, horax, etc., were shown, which had heen formed in suspension in gelatine and other solutione.

February 10, 1872.]} SCIENTIFIC PRESs: 83 NM ECHANICAL Procress Friction Gearing vs. Belts and Cog Wheels. Experiments in the uso of friction gearing—that is, of pulleys transmitting power, by direct frictional contact between the sinooth faces of the driving and the driven pulley instead of hy means of belts or y cogs meshing into each other—have been very freqnontly made, and in mauy cases with remarkable snecess. So cmphatic, are the recommendations of this method of gearing, giveu by men who have tried or witnessed its operation, that it is somewhat a matter of surprise that it has not heeu more generally adopted. It is claimed by many such persons to be equally well ndapted to the propelling of gang, umnlay or cirenlar saws, mill burrs, or in fact almost any description of machinory, and to the transmission of any amonnt of power with tle same or cyen greater usoful effect than when belts or cog wheols aro omployed. In the vicinity of Clinton, Towa, some years ago, friction pulleys wero introduced in a saw-mill with such complete success in point of oconoinmy aud convenience, that they soon hecamo an established institution thronghont that entire rsgion, superceding helts altogether, the latter bsing in eomo instances thrown ont at a heavy expense to give placo to the now order of things. Tho pulleye usod in this case were built of soft and tough wood, strongly put together by thoir segmente in such a manner as to presont the least possihlo end grain of wood to the eurface. They were placed on the main shaft, to which the powsr was applied hy tho engino crank or taken from the water wheel, as tho case might he, in the ordinary manner. The faces of the pulleys were cither parallel to the shaft or beveled at any angle required, according to the direction of the counter shafts to which the power was communicated. The segments of tho pulleys were glued or painted together and their facos turned off perfectly true. It was found that thsy required about one-third more width of face than would he necsssary if belts were used. In one case, two gangs were run, each with a friction pulley three feet in diameter and having 24 inches face. For a mulay or rotary saw mill, a pulley of from 12 to 16 inches face was found sufticieut. A friction pulley, tsn inches in diameter with six-inch face, was descrihed as giving more useful effect and heating the hoxss less than when the same pulley was used with a fonr-inch helt. From the numerous experiments made, the conclusion was reached that a pulley of 20 inches faco would successfully transmit 50 horee power without undue wearing or heating. The epecial advantages claimsd for this method were the saving of the expense of providing belts and loose pulleys and keeping them in repair, Tho mills were so arranged that each machino was run with its own counter shaft, geared either to tho engine shaft or to ono of the main counter shafts so that each workman could control the operation of his own machine indopendently of tho others, and with no throwing off or putting ouhelts. ‘Ths pulleys on the counter shafts were of iron and very strong, each having the sams face, of course, as the driving pulley, hut being of any desired diameter, according to the motion to be obtained. By msane of a movable bearing operated hy a lever, the iron pulley was readily brought in contact with its driver, the motion necessary for this purpose being less than one-eighth of an inch. The statement that, for the proper working and durability of a friction pulley, it ehould he so made as to present as little snd grain as possihle to the surface, is emphatically disputsd by experienced workmen, who claim that the precise opposite to this is the true method, and that the pulley should he so made as to offer the end grain to the contact of the other pulley to the ntmost practicable extsnt. To accomplish this purposs, the pulley is made of segments of wood, cut ont of a plank iu the shaps of a fan, the grain run. ning parallel with one side of the fan, and the end grain being represented in a slightly oblique manner at the outer or circular edge. These segments are put togsther strongly, and so arranged that the grain shall not run in the same direction iu two pieces in contact with each other, but cross in much the same manner as the furrows iu the upper and under millstone. The object ofthis is to prevent the face of the pulleys from too grsat tendency to wear in any given direction. The rim of the whesl, ag it may he ealled for covenience, is hnilt up hy laying ths first tier of segments, making a eomplete wheel of the thickness of the plank, flat upon the bench, and placing tho other layers succsesivoly upon this, hreaking joiuts and crossing the grain as already indicated. The layors are vory strongly scenred to each other with wrought nails, heside which glue or whito lead is laid on hetween them. ‘The rim hsing complete, mortises or guins are made to receive the pads of the spider at the end of the radial arms, these gains heing somewhat larger than the pads, and ths space thus given boing billed hy ths insertion of keys, one on each side of ths pad, entering from opposits directionsand overlupping cach other, the whole leugth of the pad, Bolts are also inserted, pass: ing through tho pad ina radial direction, with countersinking on the face of the pulley aud a nut ou the inner ond. ‘Tho countorsink is afterward filled hy plugging, over tho head of the holt. The conflict of testimony iu regard to tho comparative eflieiency of the pulloys iu which tho ond grain is prosented to the enrfaco and thoso in which it runs lengthwise with tho circumference is somewhat surprising, as the point is easily subjected to a practical tsst. Most mechanics will take ground without hesitation in favor of end grain, as less liahle to yicld and curl or ‘*hroom” up, whon subjected to powerful aud constautpressure.—Leffel's Mechanical News. Notzine Iron.—Nothing is moro noticeahle than the various chauges which have been made in the method of finishing iron in rolling mills during the last five years. A few years ago our mills furnished all their irou in hars, sheets, rails, or such shapes as were demanded hy soparate estahlishments. Of late the iron manufacturers have added to their mille other hranchee of iron working, which can he dons hy thsw at much less cost than hy those who were simply purchasers from the mills, and who lost considerahle in the ehape of ‘‘ecraps” in working up the iron jn various articles. Said ‘‘scrap”’ was necesearily brought hack to the millagain and sold at a greatly reduced rats. Thus it will be seen that the rolling mill that finishes ths iron direct into nuts, bolts, horse shoes, washers, railroad chairs, etc., possessea a great advantage in making these articles, which are heginning to hs viewed as a part of the rolling mill husiness, Galvauizing eheet iron, making gas pipe, strap hangings, and many other things are now made by rolling mills with more profit to themselves and the puhlic, tlian by the old method. Properly managed, the finishing of iron into these and other articles cannot fail to prove profitahle to the manufacturer. Trustine Corron Gins.—A series of interesting experiments have heen proposed at Manchester, England, for the purpose of testing the merite of the various cotton gins, for working different kinds of cotton, or ssparating tbe fihre from the seed. The points to be dstermined for each gin, and in respect to each variety of cotton are:—First—the speed of working, as tested by tho time in which a given quautity of ssed cotton can be ginned; second— The facility of working as tested by the quantity of power consumed in the operation; third—The quality of working, as tested hy the conditiou of the ginned fihre and the soparated seed respectively. In order to make the experiment as conclusiveae possihle a eeries of very ingsuious regulations have been framed to exclude the possihility of any kind of error or deception. Three principal classes of gins have hesn entered for competition namely, the roller gins, knife and roller gins, and eaw gins. Such tssts might be made with many other kinds of machinery, much to the advantage of the public and to all reully meritorious inventors. Aurating WatTrrR.—A contrivance of recent date for aerating water produced from the condensation of steam, comprises a tank with a eeries of porous or open work partitions, some containg wool and felt, with the spaces hetween filled with coke and chalk. The last compartment has a psrforated hottom, through which air is forced and rises in minute hubbles. . From an interesting article iu a recent issue of London Zimes, we lsarn that steam cultivating machinery is coming into very general use in England. One large firm have besn ssnding ont from eight to ten plowing sngines per week, most of which are for uee in districts where they can be

hired by several different farmere, 4 ; BCIENTiFIC Progress, The Permanent Gases. It is a generally received opinion that all gases are mere vapors of liquids that hoil nt very low tempsratures. Thns, whils watsr hoils at 212 , commou cther hoils at 96°, and sulphurous acid at U. Consequently, while water is always a solid or a liquid, in all parts of the earth, ethsr would he a psrmuauent gas in any place where the highest tropical temperature provailed, and snlphurous acid is always n gas except in ths eold of the polar regious. yon merenry, when exposed to a temperature euilicioutly high, hecomes transparent gas, and carhonic acid gus, when exposed to a temperature sutliciently low, becomes first a ysllowish liquid, aud then a beautifnl, snow-white solid. ‘The only ditfereuce, then, hetwcon commou snow and carhonie acid snow is that ths one is much colder than the other, while, on the other hand, the only differouce betweon carhonie acid gas and mercury gas is that tho one requires a higher temperature for its existouce thau the other. There are cortain gasce, however, which no degree of cold yst reached has reduced to the liqnid, far lese to the solid form. Prominent amongst these are oxygen and hydrogen—the gases that, comhined, form water. But after it had hesn ohserved that inteuse cold tended to reduce all gasee and vapors to the liquid form, theee gases were cooled with freszing mixtures; etill they remained in the gaseous state, although msrcury became solid, and alcohol, unless very pure, hecame thick aud pasty. After a time, a still more powerful freezing mixture (liquefied laughing-gas) was discovered, and hy a powerful steel pump was forced into a large iron receiver until it hecame liquetied with the pressure. When a little of this liquid was poured into the air, it evaporated, and produced the greatsst degrss of cold ever ohserved— 257° Fuh, Even then, oxygen and hydrogen did not liquefy, hut maintained their condition as clear and beautiful gases. But cold aloue was not the only agent hrought to hear on these gases. They were eubjected to immense pressurs, far exceeding anything with which ws are familiar in ordinary life. Nattersr constructed a eeries of very finely made steel pumps. With one of thsse, he condensed one of the gases into a strong vessel until it occupied but the three-hundreth part of its original hulk. ‘Then, with a etill more powerful pump, hs condensed this already deueo gas, so ae to reduee it still further. It will readily he seen that, hy employing gae in a condsnsed state, it was much easier to force it through the valves of the second pump than if gas at the ordinary pressure had heen used. In this way, hy working with gas gradually increasing in deneity, he finally ohtained a pressure of 3,000 atmospheres, or 22% tons to theiuch. If we have no idea of a temperature of 257° helow zero, ueither can we fully grasp the enormous pressure expressed hy the figures 2224 tons per squareinch. Most solid suhstances would he crushed to powder under snch a pressure as this. And yet to this wonderful pressure did Natterer subject oxygen and hydrogsu. But even that temperature and pressure madezno impression on them, at least so faras change of form is concerned. But thatwhich Natterer, aided by all the resources of modern science, failed to do, chemical affinity does instantly and perfectly. Mix the gases iu proper proportions and hring the smallest flame into contact with them, so as to produce ignition, and they will instantly rush togsther with a loud report, combine and form a perfect liquid, water. It is perfectly obvious that the elementary atoms of this new liquid water, must he hsld together hy a force euflicisut to overcome their expansive force, We have seen what this expansive force is capahle of resisting, and consequently we can form 2 comparative sstimate of the power of chemical affinity.—Condensed from Phin’s Chemical History. Votoanio Ervptions.—Archdeacon Pratt, by discussing the amount of prscession in a glohe with a molten nucleus, finds conclusive evidsnce of Sir Wm. Thompson’s opinion that the earth is solid, and that, therefore, volcauic eruptions are attributable to some other cause than the one popularly assigned. His view is confirmed by numerous recent observations, which indicate that the increase of tsmperature, helow the sarth’s eurface, soon reaches a limit. THe Sanp Buast.—The uniform success which has attended the use of the sand hlast has sufficiently proved its reliahility, and the numerous purposes to which it can he applied, promiss to rendsr it ons of the most useful iuventions that have heeu of late hrought into public notice. By simple moditiestions it can ho mads to snpercede the present slow and costly process for shaping grauits and othsr hard stones, for rock drilling aud for polishing castings, or grindiug aud engraving glass. The cost of working it iee#trsmely small and there ueed he no loss of ths sand employed, ae it can be constantly restored to the feeding hopper, together with the particles driven from the material. The action of the sand upon a hard surface appears to he due to the work performed by cach angular particle that strikes, and which in striking carries away with ita particle, of course far smaller thau itselt, sud the reason why the softer materials resist the wearing action, is due to tho elasticity which repets the particles. Asa proot of this, it may he mentionod that while perforated shield plates of lace, golatine, or ruhher bear a prolonged exposure to tho sand, unharmed, stencils of thin sheet steel or hrass curl up, and are destroyed.— Engineering. Tue Pwneumatio Sewaoz Systemw in which air is the power employed for cleauing the sowers of matter otherwise likely to accumulate, is discussed with much interest hy eome of our foreign exchanges. The plan is to divide a city into complexes and suh-complexes, a suh-complsx coneisting of ahout 200 houses, and a complex comprising all the sub-complexes within a radius of 2,500 feet. Exch complex has a large air-tight cast iron reservoir, and each suh-complex a small one connecting with the muin reservoir and with the houses, hy means of pipes provided with valvss and cocke, hy which all circulation of air may be prevented. The air insido is exhausted hy means of a largs air pump driven in connsction with the main ressrvoir hy means of a powerful steam engine, and then the outer air, pressiug upon the contents of the pipes, forces them into the reservoirs. By this means the pipes may all be cleared in lsss than five minutes, their contsnts first passing into the eub-rsservoirs, and then into the main one. ‘This simple and eminently eanitary system has for some time past hesn in successful operation in the city of Prague, Bohemia, and is heing introduced into other European cities. —Lz. Accuracy or TELEGRAPHIC ESTIMATES OF Loneirupes.—The great accuracy with which diffsreuces of longitude can he ascertained by the magnetic telegraph is illnstrated hy soms of the determinations for the United States Coast Survey. Where the longitudes were estimated hy four differsnt circuits, the greatest difference between any two determinations was twentyeight thousandths of a second, equivalent to about thirty feet, the mean error being lsss than one millionth of the distance hetween the two objective points, which, in some cases, as in that hstwesn Cambridge and San Francisco, was 3,080 miles. New Usz ror Expcrriciry.—Electricity has achieved a newtriumph. Already employed to restors vigor and nimbleness to the gouty limhs of decrepit bons vivants, the recent discoveries of Dr. Bernier, a French physician, show electricity to he an efficient remedy for the evil effects of excessive drinking on the human nose. The doctor mantains that, hy the application of an electric current to noses even of the most Bacchanalian hue, the flesh may he made ‘“‘to come again asthe flesh of a little child ;” and he supports his assertion hy a case performed on a female patient of his own, a woman of high rank.—Sci. Am. Tue Foes Puants or Canapa.—Dr. J. W. Dawson, of the Geological Survey of Canada, has just puhlished hie report ou the fossil land plants of the Devonian and Uppsr Silurian formations of Canada. In this report, he has catalogued or described more than 120 species of land plants found in formations older than the carhoniferousin Canada, thus placing the knowledge of this old flora in advance of that of any other portion of the world. A New Mops or Forinne Perrror CrysTaLs.—Prof. Schultzs states that by tbe use of gelatinizing liquid as a solvent, erystals of various substances may be ohtained completely formed. In proof, a number of fine crystals of sugar, horax, etc., were shown, which had heen formed in suspension in gelatine and other solutione.