Volume 35 (1877) (426 pages)

September 15, 1877.] MINING AND SCIENTIFIC PRESS 163 Mf ecHANica *P rocress. AD The Value of Dry Steam. J. Haug, a mechanical engineer, writes for the Polytechnic Review sous points on the loss and danger of priming iu boilers, and sume ways of guarding ayainst it. Ile says: The use of dry steam is not ouly a source of ceonomy in ths builer, to prevent an wunecessary expenditure of heat, hut still more so in the engine, where water contained in the steam not only does no work, but cools the metal in the eteam cylinder, ete., thereby eausing a fresh expenditure of steain to heat these parts np again. If with evory pound of steain at 60 Ibs, pressure a half pound of water is carried over, a quantity not unusual in a priming boiler, the latter has to be heated to the boiling point, and 7, of the heat is expended in heatmg the water carried over. The feed pump has, of course, 50 mere work to do, rat the heater will have its ctlieioney reduced by one-third. “To avoid priming, a boiler should have a good circulation, and be large enough to do its work withont forecd tiring. A good circulation will also improve tho ovaporative ctlicicucy of a boiler, as tho steam (which is a bad conductor of heat) is quickly removed froin tho heated plates, and now water constantly fullows it. A steam trap, either fixed in a steam dome, or in some high placo in the steam pipe, will drain the water trapped iu it back to the boiler, thus saving heat expeuded in heating it. Sometimes the steam pipe is exteuded downward from the throttle valve on the eugine, so as to form a cul de sec for the aceumnulation of water, which cau then be pumped hack into tho hoiler. A superheater, heated hy the waste gases, nay serve to evaporate the water carried over, and to dry the steam thoroughly; hut if the priming is excessivo, it will not be suthcicn’ for this purpose. lf water is carried into the cylinder, it will cool the motal, with which it comes in contact; the amount of this depends upon the surface expose, the difforence of initial and tinal temperaturo, the specific heat of tho metal, the piston sapocd, tbe rate of expansion, etce.; and the variable character of these conditious makes it exceedingly diflicult to give a figure for the loss thus curred, but it is certainly cousiderable, and may range up to°30%. In non-expansive cngiues this water is partly evaporated on the hack stroke, abstracting heat froin the cylinder increasing the back pressure, and in a condensing engino reqniring moro injection water and entailing niore work upon the air pump. In expansive engines the re-cvaporation of this water takes place during expausion, whereby the final pressure is somewhat increased, but this is vastly overhalanced by a great fall in the initial pressure; for engines using 60 pounds of steam, cutting off at onesixth or one-eighth, the initial pressure on the indicator card may often he 20 to 30 pouuds below the hoiler pressure, Even a steain jacket would be powerless against a great in{lux of water, as its surface and rate of conduction are necessarily limited. Last, but not least, the danger of water in the cylinder must be considered, tho result generally being hroken pistons and rods, knocked-out cylinder heads, aud, as a natural consequence, a general smash-up. Propelling by Pumps. Attempts have been made at various times to move boats by forcing jets of water through openings in the sides or cnds of the hulls, and hitherto these experiments have not heen successful, A more recent experiment in this direction has resulted favorably, and a towboat, 13.11 meters (43 feet) long, has been constructed that employs a common steam pump iu place of an engine and propeller. A writer in Scribner's Monthly gives the followiug details: The boat has a steam boiler of moderate size, and is, in other respects, one tow-boat of the usual pattern. Four pipes, 64 milliineters (24 inches) in diameter, are laid the whole length of the boat inside, and about a meter below the water Hine. At the bow two of these pipes open the whole size of the pipe directly into the outer water, and at the stern they are reduced to a nozzle of only 22 millimeters diameter. The other pair of pipes are arranged in the same manner, except that the nozzles are placed at the bows. A steam pump is connected with each pair of these pipes, and when at work takes the water in at the bows and ejects it in a powerful stream at the stcrn, and thus forces tbe boat ahead at a good speed. To reverse the direction, the pump takes the water from tbe stern through the othor pair of pipes and forces it out at the bow, andthe hoat instantly reverses its direction. The novelty in this invention consists in the use of a reduced pipe or nozzle at the place of discharge. By meaus of the two nozzles the hoat may be easily steered independently of the rudder by using one or the other of the two pipes alteruately. The advantages claimed for this system of propulsion are the cheapuess of the apparatus and the absence of ripple or disturbance of the water. The escaping water is so far below the surface that it creates no disturbance, and the hoat only makes the wave that hreaks from the bow, aud, in this respect, this method of propulsion may fulfill the demand for a steam tow-boat for eanals. Oua trial trip at sea, the boat nade a voyaze of some length in safety and at good speed, Pistons which Require no Lubrication. In descrihing a form of compouud engines for working steam of very Ligh pressure, Mr. Loftus Perkins, in @ paper read beforo the Institution of Mechanical Engincers, cxplained that ho fouud some difficulty in getting ordiuary pistons and valves to staud the high temperatures, or, to use his own language: “In working these high pressurcs (350 Iba. persquare inch) with great expansion, the ordinary mode of packing the pistous was found unsatisfactory, and tu overcome the ditliculty the eompound piston was dovised. The provalent scoring and cutting ef engine cylinders was etfectunlly remedied by the discevery of the compound metal, of which the packing rings arc made, which requires no lubricating matetial, Many ceylinders titted with piston rings mado of this metal have heen several years at work, and havo been often cxamiued, the cylinders showing no signs of wear, the wear taking place ou the rings only, which may he easily and inexpensively renewed as required; and experienco has proved that, with these pistous, the longer au engine is worked the more perfect does the surface of the cylinders become, and tho less wear results to the packing rings. This metal for piston-packing rings is composcd of five parts tiu and 15 parts copper, and has since heeu used by several othcr makers for ordiuary engines with great success, When this metal is used, uo oil or grease is required to lubricate the eylinders—-a great advantage, particularly whon the engines are fitted with surface condensers.” Of ouc engine tho writer says: ‘ After being in use nearly 13 years, the piston-packing and valve rings, made of the special metal, were found in excellent condition after 18 mouths’ workiug without lubrication since last examined.” i Our Domestic Metals. Professor Thurston makes the following points in the Popular Science Monthly: “his country has for years heen importing cast iron, while domestic products of equal aud even greater intrinsic value sell at a lower price. Other similar instances of unwisdom are cited by Professor Thurston, as, for example, tbe fact that we are importiug boiler-plate at 1] cents a pound, when we can purchase American steel, vastly superior in all respects for the special purposcs to which the former article is applied, at eight ceuts, Again, we import vast quantities of foreigu steel tools, when at Pittsburg and elsewhere we make steel fully its equal. In New England and Pennsylvania we have ores from which is made tbe tiuest castirou orduance in the world. In Ohio we make a inctal for car-wheels such as is never seen in Europe, and of such tenacity and elasticity that foreign enyineers listen inercdulously when it is descrihed. Our Lake Champlain ores make an iron fully equal to Swedish for conversion into steel; and around Lake Superior and in Missouri we have deposits from which comes Bessimer metal, far superior to the phosphoruscharged metal weimport. New Jersey supplies us with zine which meets with no competition as apure metal, and which can be used without purification, even for chemical purposes; and our native copper is absolutely free from admixture with injurious elements, It is time that these facts should be known, and that the people should disabuse their minds of the idea that, becanse 1 commodity is ‘imported,’ it is therefore of greater intrinsic value than a domestic product.” Brastixe Coat witn CompressEp AIR.— With a view to facilitate the getting of coal without the use of gunpowder, Mr. Samuel Marsh, of Nottingham, proposes the use of compressed air in cartridges placed in direct connection with pumps, tho pressure in such cartridges being increascd until the explosion takes place. He also has a portahle exploder, charged with compressed atmospheric air by the same machinery, which is then taken and connected to tbe cartridge. The cartridge, which is composed of iron or steel, in the form of acylinder, is securely rammed or stemined iu; and when connected to the exploders the valve is opened, and the admission of air bursts tho cartridge and hrings down the coal, After the blasting operation is finisbed the exploder is unscrewed, and ready to be charged again, TouGHENING GLass By ComPREssION.—In the Siemens’ glass works at Dresden, there is now manufactured a product which has the same properties as La Bastie’s tempercd glass, the streugth being communicated hy the pressure of metallic rolls. Plates can he made, by this method, of much larger dimensions than by La Bastie’s. They have w beautiful look, and can he ornamented with the most complicated designs, at a less cost than ordinary glass, Siemens claims that glass manufactured by his process has a greater strengtb than tempered glass, in the ratio of five tothree. When broken it shows a fibrous structure, while La Bastie’s is crystalline. ow & ScientiFic ‘PRoGRess. Geological Progress. We Icarn from a foreign exchange that MM. Delesse aud de Lapparent have prepared a valuahle resume of the geological works published during the years 1875 and 1876. Their work covers 184 closely-priuted pages ; we have room only for a few brief uotes, The mean hight of Kurope, according to Leipoldt, is 206,838 meters; Humboldt’s estimate was 20311, The inerease of tempcraturo at given depths below the surface, is greatest im the equatorial regions, Prestwich has confirmed the views of Dana, Carpenter and Wyvillo-Thomson, relative to the distribution of ocean temperatures. ‘The resistance of roeks to crushing is diminished (in some eases as much as 80 per cent.) by tho absorption of water. Tho plasticity of surface rocke is intimately dependent on their argillaceous character; hut at great depths, pressure, water and increased temperature, make all rocks plastic. Th. Nubener has demonstrated, iua lignite, the existonco of a wultitude of microscopic quartz erystals, which he attributes to a slow decomposition of infiltrated silicates hy the humic acid. By trexting a Vesuvian pumice, which seemed to be ainorphous, with fluorhydrie acid, Fonque has oxtracted from it crystals of feldspar, pyroxeno, amphibole, peridote, magnesian mica, and oxidized irou, Ho has also shown that the minute cavities of the pumice were decked with microscopic crystals of amphigene. The contest ppepecting the organic character of the Hozoon still continues; and even if its animal origin is granted, doubts are thrown on the assuined age of tho Lawrentiau formation, in which it is found. Oweu has studied the bones of a curions carnivorous reptile, Cyxodrakon major, from southern Africa. He assigns it, together with other sinilar reptiles from the same region, toa new order, Vheoriodontes, having the dentition of carnivores, He thinks that their high organization cannot be explaiued hy the hypotheses eithcr of Darwin or Lamarck. Forests improve the soil much more rapidly than coppicewood; the humus exhibits a very differeut composition from that of the rocks upon the surface of which it is formed. Experiments with Tresca’s apparatus seem to show that cleavage and lamination may be due to the same cause, and that the schistosity of gneiss may be no evidence of stratification. Insects’ Breathing Apparatus. In a recent work on the morphology of the tracbeal or respiratory system of isects, reviewed hy the New York /ndependent, Dr, J, A, Palmen arrives at the conclusion that the primitive number of pairs of spiracles or breathing holesin insects is eleven, thus agreeing with the views previously expressed by Packard in a brief essay published on the subject in 1873, Palmen’s work comprises 150 pages, and is quite exhaustive,as a German essay should be. He believes that the tracheal system was at first, in its primitive form, open—é. ¢., consisting of a series of tubes connected by spiracles or holes with the outer world. Incertain aquatic insccts the system became closed, the larva breathing by external gill-like appeudages. As to the origin of the trachee Butschli (1870) believed that their mode of origin was the saine as the silk glands, and that the two sets of organs were homologues, and that they were derived primitively from the segmental organs of worms, which are arranged in pairs along the hody of the latter animal, In 1873 Packard suggested that the air-tubes may have originated indepeudently within the hody, and afterward formed a connection with minute pores leadiug through the skin. In 1874 Semper expressed the same views as those of Butschli, which in the ycar after was accepted by Mayer. Moseley regarded them iu 1874 as dermal glands modified. Packard then suggested that the tracheal system might be derived from the water vascular system of certain low worms; while, in a late paper on the development of the Lopidoptcra, Hatschek couceives that the air-tubes are derived from respiratory portions of the skin much enlarged. Finally Palmeu appears to adopt the view that the trachew may have originated from the segmental organs from the jointed worms. This shows how conjectural is our knowledge of the origiu of these interesting organs. He conceives that the excretory function of the primitive lung-sac was afterward replaced by an absorbing function, and the sac or tube became a respiratory organ—viz., a trachea—which (at first simple and sac-like, due origiually to an inpushing of the skin) became longer and branched, until it assumed the present form, With this view we should not be disposed to find fault as a provisional hypothesis. Cotors or Mars.—In the observations about to he made of Mars at the time of its opposition, which occurs in this month, Professor Proctor thinks that it will he a favorable opportunity for a more careful study of tho varieties of light and shade and of color in this plauet. In comaring pictures of the same object made by diferent ohservers, great difference is apparent, and can he traced to this cause. The notion that the surface is divided into ruddy and green portions, and the white polar crown cape and occasional white eloud markings, is far from the truth. Why Mars’ Moons were not Found Before. Prof. Simon Neweomh writes to the New York Tribune in answer to the above question as follows; The answer is that Mars is now nearcr to the earth than it has heen at any time since 1$45, when tho great telescopes of ths present had hardly begun to he known, The next opportunity for seeing them occurred in 1862, but we may snppose they were then not especially sought for with the two or three telescopes Which alono would show them, The next favorablo opposition was in 1875, but Mars was then so far south of the equator that it could not well be observed in our latitudes, The preseut oppositiou is about tho best possible for ohscrvatiou in the middle latitude ef our hemispheres, because tho very smallest deviation from greatest possible approach to the earth arises froin tho opposition occurriug a few days after the planet reaches its position, and this throws it farther north in declinatiou than it would be at tho time of absolutely nearest appan The next opposition will occur in ctober, 1879, and there is somo hope that tho satellites may then again be observed with the Washington tclescope. During the 10 years following they will probably he entirely invisiblo with all the telescopes of tbo world, beeansc, owing to the preat eccentricity of the orbit of Mars, the planet will be too far away at the times of oppesitiou. In 1892 a favorable opposition will again occur. During the present year it is hardly likely that tbo satellites will be visible after October. A New Mertar.—Serge Kern announces, in Comptes Rendus, his discovery, in June last, of a new platinoid metal which he calls duvyum, in honor of Sir Humphrey Davy. It is hard, silvery in luster, malleablo at red heat, readily soluble in aqua-regia and very feebly in boiling sulphuric acid, yielding a yellow precipitate with caustic potash. Sulphureted hydrogen, passed through a diluto solution of the chloride, yields a hrown precipitate which hecomes black upon drying, Potassic sulphocyanide, with the same solutiou, is colored red; and if the solution of davyum in KCyS is concentrated, a red precipitate is obtained. Sp. gr. 9.385 at 25° C, Kern thiuks that in Mendelejeff’s proposed classification of the elements, davyum is the hypothetical element placed between molyhdenum and ruthenium, in which case its equivalent should be 100. It would then rank as the second confirmation of Mendclejeff's predictions, gallium having been the first. It is probably taro, The platiniferous sand does not contain more than .00045 of davyum. Tux Haypen Surveys.—A telegram from Washington gives the following interesting information: James Stevenson, executive officer of Prof. Hayden’s geological survey, has just returned from the field of exploration. Stevenson says that several divisions of the expedition are still at work and approaching the completion of their labor for the season, Each division has ten thousand square miles assigned it for examination, and reports just received from the seats of divisions indicate that they will finisb their field work by the first of October. The result of this year’s examinations will be equal in importance to that of any previous year. The work of survey in the present year will be in the Territories of Idaho, Wyoming, and Montana. A Texescore Iptr.—The mammoth telescope completed some two years ago by Alvan Clark & Son, of Cambridge, for L. J. MeCormick, of Virginia, the reaping-machine manufacturer, still lies in the factory. This instrument has an object-glass of 26 inches, is nearly 20 feet in length, and was made for $38,000 in gold. <A portion of the cost only has been paid by Mr. McCormick; and the reason that he has never taken the instrument is said to be that he is nnable to decide to which of the ohservatories and colleges that have hegged for it he will give it. It is also nnderstood that Mr. McCormick is in hopes of receiving a legacy to assist iu paying for the telescope. In all probability, if the instrument is ever taken, it will he douated to some institution in Virginia, says the Boston Pranseript, Saniras.—The oxidation product of turpentine (analogous, it is said, to the principle of the famous Hucalyptus globulus) discovered by Messrs. Kingzett and Zingler, is now manufactured on a large scale for use as an antiseptic and disinfectaut, under the name of sanitas. For proofs of its usefulness, says /ron, in these capacities readers may refer to the experiment detailed in the paper read by Mr. Kingzett before the Society of Arts. We have seen several instances of arrested putrefaction effected by means of sanitas, and intend further testing it, A variety of it is made for toilet purposes, and appears to be deserving of trial. Garvanic CRYSTALLIZATION.—Tbe journal of the Russian Chemical and Pbysical Society, says Natwre, contains observations, by Shidlovsky, on the microscopical crystallization of various metals under the influence of a galvanic current, Thedondritric agglomerations of crystals form very speedily; their hranches spread out from the cathode to the anode. plate, vibrate on reaching it and collapse; this process is repeated till the space between the plates is filled with a spongy metallic mass. Each metal has a characteristic ramification. The crystallization does not appear when the anode ig gold or platinum.

September 15, 1877.] MINING AND SCIENTIFIC PRESS 163 Mf ecHANica *P rocress. AD The Value of Dry Steam. J. Haug, a mechanical engineer, writes for the Polytechnic Review sous points on the loss and danger of priming iu boilers, and sume ways of guarding ayainst it. Ile says: The use of dry steam is not ouly a source of ceonomy in ths builer, to prevent an wunecessary expenditure of heat, hut still more so in the engine, where water contained in the steam not only does no work, but cools the metal in the eteam cylinder, ete., thereby eausing a fresh expenditure of steain to heat these parts np again. If with evory pound of steain at 60 Ibs, pressure a half pound of water is carried over, a quantity not unusual in a priming boiler, the latter has to be heated to the boiling point, and 7, of the heat is expended in heatmg the water carried over. The feed pump has, of course, 50 mere work to do, rat the heater will have its ctlieioney reduced by one-third. “To avoid priming, a boiler should have a good circulation, and be large enough to do its work withont forecd tiring. A good circulation will also improve tho ovaporative ctlicicucy of a boiler, as tho steam (which is a bad conductor of heat) is quickly removed froin tho heated plates, and now water constantly fullows it. A steam trap, either fixed in a steam dome, or in some high placo in the steam pipe, will drain the water trapped iu it back to the boiler, thus saving heat expeuded in heating it. Sometimes the steam pipe is exteuded downward from the throttle valve on the eugine, so as to form a cul de sec for the aceumnulation of water, which cau then be pumped hack into tho hoiler. A superheater, heated hy the waste gases, nay serve to evaporate the water carried over, and to dry the steam thoroughly; hut if the priming is excessivo, it will not be suthcicn’ for this purpose. lf water is carried into the cylinder, it will cool the motal, with which it comes in contact; the amount of this depends upon the surface expose, the difforence of initial and tinal temperaturo, the specific heat of tho metal, the piston sapocd, tbe rate of expansion, etce.; and the variable character of these conditious makes it exceedingly diflicult to give a figure for the loss thus curred, but it is certainly cousiderable, and may range up to°30%. In non-expansive cngiues this water is partly evaporated on the hack stroke, abstracting heat froin the cylinder increasing the back pressure, and in a condensing engino reqniring moro injection water and entailing niore work upon the air pump. In expansive engines the re-cvaporation of this water takes place during expausion, whereby the final pressure is somewhat increased, but this is vastly overhalanced by a great fall in the initial pressure; for engines using 60 pounds of steam, cutting off at onesixth or one-eighth, the initial pressure on the indicator card may often he 20 to 30 pouuds below the hoiler pressure, Even a steain jacket would be powerless against a great in{lux of water, as its surface and rate of conduction are necessarily limited. Last, but not least, the danger of water in the cylinder must be considered, tho result generally being hroken pistons and rods, knocked-out cylinder heads, aud, as a natural consequence, a general smash-up. Propelling by Pumps. Attempts have been made at various times to move boats by forcing jets of water through openings in the sides or cnds of the hulls, and hitherto these experiments have not heen successful, A more recent experiment in this direction has resulted favorably, and a towboat, 13.11 meters (43 feet) long, has been constructed that employs a common steam pump iu place of an engine and propeller. A writer in Scribner's Monthly gives the followiug details: The boat has a steam boiler of moderate size, and is, in other respects, one tow-boat of the usual pattern. Four pipes, 64 milliineters (24 inches) in diameter, are laid the whole length of the boat inside, and about a meter below the water Hine. At the bow two of these pipes open the whole size of the pipe directly into the outer water, and at the stern they are reduced to a nozzle of only 22 millimeters diameter. The other pair of pipes are arranged in the same manner, except that the nozzles are placed at the bows. A steam pump is connected with each pair of these pipes, and when at work takes the water in at the bows and ejects it in a powerful stream at the stcrn, and thus forces tbe boat ahead at a good speed. To reverse the direction, the pump takes the water from tbe stern through the othor pair of pipes and forces it out at the bow, andthe hoat instantly reverses its direction. The novelty in this invention consists in the use of a reduced pipe or nozzle at the place of discharge. By meaus of the two nozzles the hoat may be easily steered independently of the rudder by using one or the other of the two pipes alteruately. The advantages claimed for this system of propulsion are the cheapuess of the apparatus and the absence of ripple or disturbance of the water. The escaping water is so far below the surface that it creates no disturbance, and the hoat only makes the wave that hreaks from the bow, aud, in this respect, this method of propulsion may fulfill the demand for a steam tow-boat for eanals. Oua trial trip at sea, the boat nade a voyaze of some length in safety and at good speed, Pistons which Require no Lubrication. In descrihing a form of compouud engines for working steam of very Ligh pressure, Mr. Loftus Perkins, in @ paper read beforo the Institution of Mechanical Engincers, cxplained that ho fouud some difficulty in getting ordiuary pistons and valves to staud the high temperatures, or, to use his own language: “In working these high pressurcs (350 Iba. persquare inch) with great expansion, the ordinary mode of packing the pistous was found unsatisfactory, and tu overcome the ditliculty the eompound piston was dovised. The provalent scoring and cutting ef engine cylinders was etfectunlly remedied by the discevery of the compound metal, of which the packing rings arc made, which requires no lubricating matetial, Many ceylinders titted with piston rings mado of this metal have heen several years at work, and havo been often cxamiued, the cylinders showing no signs of wear, the wear taking place ou the rings only, which may he easily and inexpensively renewed as required; and experienco has proved that, with these pistous, the longer au engine is worked the more perfect does the surface of the cylinders become, and tho less wear results to the packing rings. This metal for piston-packing rings is composcd of five parts tiu and 15 parts copper, and has since heeu used by several othcr makers for ordiuary engines with great success, When this metal is used, uo oil or grease is required to lubricate the eylinders—-a great advantage, particularly whon the engines are fitted with surface condensers.” Of ouc engine tho writer says: ‘ After being in use nearly 13 years, the piston-packing and valve rings, made of the special metal, were found in excellent condition after 18 mouths’ workiug without lubrication since last examined.” i Our Domestic Metals. Professor Thurston makes the following points in the Popular Science Monthly: “his country has for years heen importing cast iron, while domestic products of equal aud even greater intrinsic value sell at a lower price. Other similar instances of unwisdom are cited by Professor Thurston, as, for example, tbe fact that we are importiug boiler-plate at 1] cents a pound, when we can purchase American steel, vastly superior in all respects for the special purposcs to which the former article is applied, at eight ceuts, Again, we import vast quantities of foreigu steel tools, when at Pittsburg and elsewhere we make steel fully its equal. In New England and Pennsylvania we have ores from which is made tbe tiuest castirou orduance in the world. In Ohio we make a inctal for car-wheels such as is never seen in Europe, and of such tenacity and elasticity that foreign enyineers listen inercdulously when it is descrihed. Our Lake Champlain ores make an iron fully equal to Swedish for conversion into steel; and around Lake Superior and in Missouri we have deposits from which comes Bessimer metal, far superior to the phosphoruscharged metal weimport. New Jersey supplies us with zine which meets with no competition as apure metal, and which can be used without purification, even for chemical purposes; and our native copper is absolutely free from admixture with injurious elements, It is time that these facts should be known, and that the people should disabuse their minds of the idea that, becanse 1 commodity is ‘imported,’ it is therefore of greater intrinsic value than a domestic product.” Brastixe Coat witn CompressEp AIR.— With a view to facilitate the getting of coal without the use of gunpowder, Mr. Samuel Marsh, of Nottingham, proposes the use of compressed air in cartridges placed in direct connection with pumps, tho pressure in such cartridges being increascd until the explosion takes place. He also has a portahle exploder, charged with compressed atmospheric air by the same machinery, which is then taken and connected to tbe cartridge. The cartridge, which is composed of iron or steel, in the form of acylinder, is securely rammed or stemined iu; and when connected to the exploders the valve is opened, and the admission of air bursts tho cartridge and hrings down the coal, After the blasting operation is finisbed the exploder is unscrewed, and ready to be charged again, TouGHENING GLass By ComPREssION.—In the Siemens’ glass works at Dresden, there is now manufactured a product which has the same properties as La Bastie’s tempercd glass, the streugth being communicated hy the pressure of metallic rolls. Plates can he made, by this method, of much larger dimensions than by La Bastie’s. They have w beautiful look, and can he ornamented with the most complicated designs, at a less cost than ordinary glass, Siemens claims that glass manufactured by his process has a greater strengtb than tempered glass, in the ratio of five tothree. When broken it shows a fibrous structure, while La Bastie’s is crystalline. ow & ScientiFic ‘PRoGRess.

Geological Progress. We Icarn from a foreign exchange that MM. Delesse aud de Lapparent have prepared a valuahle resume of the geological works published during the years 1875 and 1876. Their work covers 184 closely-priuted pages ; we have room only for a few brief uotes, The mean hight of Kurope, according to Leipoldt, is 206,838 meters; Humboldt’s estimate was 20311, The inerease of tempcraturo at given depths below the surface, is greatest im the equatorial regions, Prestwich has confirmed the views of Dana, Carpenter and Wyvillo-Thomson, relative to the distribution of ocean temperatures. ‘The resistance of roeks to crushing is diminished (in some eases as much as 80 per cent.) by tho absorption of water. Tho plasticity of surface rocke is intimately dependent on their argillaceous character; hut at great depths, pressure, water and increased temperature, make all rocks plastic. Th. Nubener has demonstrated, iua lignite, the existonco of a wultitude of microscopic quartz erystals, which he attributes to a slow decomposition of infiltrated silicates hy the humic acid. By trexting a Vesuvian pumice, which seemed to be ainorphous, with fluorhydrie acid, Fonque has oxtracted from it crystals of feldspar, pyroxeno, amphibole, peridote, magnesian mica, and oxidized irou, Ho has also shown that the minute cavities of the pumice were decked with microscopic crystals of amphigene. The contest ppepecting the organic character of the Hozoon still continues; and even if its animal origin is granted, doubts are thrown on the assuined age of tho Lawrentiau formation, in which it is found. Oweu has studied the bones of a curions carnivorous reptile, Cyxodrakon major, from southern Africa. He assigns it, together with other sinilar reptiles from the same region, toa new order, Vheoriodontes, having the dentition of carnivores, He thinks that their high organization cannot be explaiued hy the hypotheses eithcr of Darwin or Lamarck. Forests improve the soil much more rapidly than coppicewood; the humus exhibits a very differeut composition from that of the rocks upon the surface of which it is formed. Experiments with Tresca’s apparatus seem to show that cleavage and lamination may be due to the same cause, and that the schistosity of gneiss may be no evidence of stratification. Insects’ Breathing Apparatus. In a recent work on the morphology of the tracbeal or respiratory system of isects, reviewed hy the New York /ndependent, Dr, J, A, Palmen arrives at the conclusion that the primitive number of pairs of spiracles or breathing holesin insects is eleven, thus agreeing with the views previously expressed by Packard in a brief essay published on the subject in 1873, Palmen’s work comprises 150 pages, and is quite exhaustive,as a German essay should be. He believes that the tracheal system was at first, in its primitive form, open—é. ¢., consisting of a series of tubes connected by spiracles or holes with the outer world. Incertain aquatic insccts the system became closed, the larva breathing by external gill-like appeudages. As to the origin of the trachee Butschli (1870) believed that their mode of origin was the saine as the silk glands, and that the two sets of organs were homologues, and that they were derived primitively from the segmental organs of worms, which are arranged in pairs along the hody of the latter animal, In 1873 Packard suggested that the air-tubes may have originated indepeudently within the hody, and afterward formed a connection with minute pores leadiug through the skin. In 1874 Semper expressed the same views as those of Butschli, which in the ycar after was accepted by Mayer. Moseley regarded them iu 1874 as dermal glands modified. Packard then suggested that the tracheal system might be derived from the water vascular system of certain low worms; while, in a late paper on the development of the Lopidoptcra, Hatschek couceives that the air-tubes are derived from respiratory portions of the skin much enlarged. Finally Palmeu appears to adopt the view that the trachew may have originated from the segmental organs from the jointed worms. This shows how conjectural is our knowledge of the origiu of these interesting organs. He conceives that the excretory function of the primitive lung-sac was afterward replaced by an absorbing function, and the sac or tube became a respiratory organ—viz., a trachea—which (at first simple and sac-like, due origiually to an inpushing of the skin) became longer and branched, until it assumed the present form, With this view we should not be disposed to find fault as a provisional hypothesis. Cotors or Mars.—In the observations about to he made of Mars at the time of its opposition, which occurs in this month, Professor Proctor thinks that it will he a favorable opportunity for a more careful study of tho varieties of light and shade and of color in this plauet. In comaring pictures of the same object made by diferent ohservers, great difference is apparent, and can he traced to this cause. The notion that the surface is divided into ruddy and green portions, and the white polar crown cape and occasional white eloud markings, is far from the truth. Why Mars’ Moons were not Found Before. Prof. Simon Neweomh writes to the New York Tribune in answer to the above question as follows; The answer is that Mars is now nearcr to the earth than it has heen at any time since 1$45, when tho great telescopes of ths present had hardly begun to he known, The next opportunity for seeing them occurred in 1862, but we may snppose they were then not especially sought for with the two or three telescopes Which alono would show them, The next favorablo opposition was in 1875, but Mars was then so far south of the equator that it could not well be observed in our latitudes, The preseut oppositiou is about tho best possible for ohscrvatiou in the middle latitude ef our hemispheres, because tho very smallest deviation from greatest possible approach to the earth arises froin tho opposition occurriug a few days after the planet reaches its position, and this throws it farther north in declinatiou than it would be at tho time of absolutely nearest appan The next opposition will occur in ctober, 1879, and there is somo hope that tho satellites may then again be observed with the Washington tclescope. During the 10 years following they will probably he entirely invisiblo with all the telescopes of tbo world, beeansc, owing to the preat eccentricity of the orbit of Mars, the planet will be too far away at the times of oppesitiou. In 1892 a favorable opposition will again occur. During the present year it is hardly likely that tbo satellites will be visible after October. A New Mertar.—Serge Kern announces, in Comptes Rendus, his discovery, in June last, of a new platinoid metal which he calls duvyum, in honor of Sir Humphrey Davy. It is hard, silvery in luster, malleablo at red heat, readily soluble in aqua-regia and very feebly in boiling sulphuric acid, yielding a yellow precipitate with caustic potash. Sulphureted hydrogen, passed through a diluto solution of the chloride, yields a hrown precipitate which hecomes black upon drying, Potassic sulphocyanide, with the same solutiou, is colored red; and if the solution of davyum in KCyS is concentrated, a red precipitate is obtained. Sp. gr. 9.385 at 25° C, Kern thiuks that in Mendelejeff’s proposed classification of the elements, davyum is the hypothetical element placed between molyhdenum and ruthenium, in which case its equivalent should be 100. It would then rank as the second confirmation of Mendclejeff's predictions, gallium having been the first. It is probably taro, The platiniferous sand does not contain more than .00045 of davyum. Tux Haypen Surveys.—A telegram from Washington gives the following interesting information: James Stevenson, executive officer of Prof. Hayden’s geological survey, has just returned from the field of exploration. Stevenson says that several divisions of the expedition are still at work and approaching the completion of their labor for the season, Each division has ten thousand square miles assigned it for examination, and reports just received from the seats of divisions indicate that they will finisb their field work by the first of October. The result of this year’s examinations will be equal in importance to that of any previous year. The work of survey in the present year will be in the Territories of Idaho, Wyoming, and Montana. A Texescore Iptr.—The mammoth telescope completed some two years ago by Alvan Clark & Son, of Cambridge, for L. J. MeCormick, of Virginia, the reaping-machine manufacturer, still lies in the factory. This instrument has an object-glass of 26 inches, is nearly 20 feet in length, and was made for $38,000 in gold. <A portion of the cost only has been paid by Mr. McCormick; and the reason that he has never taken the instrument is said to be that he is nnable to decide to which of the ohservatories and colleges that have hegged for it he will give it. It is also nnderstood that Mr. McCormick is in hopes of receiving a legacy to assist iu paying for the telescope. In all probability, if the instrument is ever taken, it will he douated to some institution in Virginia, says the Boston Pranseript, Saniras.—The oxidation product of turpentine (analogous, it is said, to the principle of the famous Hucalyptus globulus) discovered by Messrs. Kingzett and Zingler, is now manufactured on a large scale for use as an antiseptic and disinfectaut, under the name of sanitas. For proofs of its usefulness, says /ron, in these capacities readers may refer to the experiment detailed in the paper read by Mr. Kingzett before the Society of Arts. We have seen several instances of arrested putrefaction effected by means of sanitas, and intend further testing it, A variety of it is made for toilet purposes, and appears to be deserving of trial. Garvanic CRYSTALLIZATION.—Tbe journal of the Russian Chemical and Pbysical Society, says Natwre, contains observations, by Shidlovsky, on the microscopical crystallization of various metals under the influence of a galvanic current, Thedondritric agglomerations of crystals form very speedily; their hranches spread out from the cathode to the anode. plate, vibrate on reaching it and collapse; this process is repeated till the space between the plates is filled with a spongy metallic mass. Each metal has a characteristic ramification. The crystallization does not appear when the anode ig gold or platinum.