Volume 35 (1877) (426 pages)

19 July 14, 1877.] ay? Ke M ECHANICAL Pp ROGRESS. faa tal was Steel Locomotive Boilers. One of the topics under consideration at the late meeting of railway inaster mechanies, at Cleveland, was the relative quality of trou and steel as material for railroad boilers. The testimony was almost unswerving in favor of steel as the best material for the shell of the boiler. We quote from a report of n conmittee as follows: With two exceptions all express themselves decidedly in favor of steel for the shell of the boiler. It is superior to iron in strength, and less ditheult to shape and put together, and seems to be in every way preferable. Those who have nsed it most extensively for this purpose are the most decided in preferring it. Not a single instance is reported where stcel in the shell of a boiler has ruptured when cold, or in heating up, or from putting cold water im the boder while hot, as so frequently occnrs in the case of the sheets of tho tiro-box. Mr. Sedgley, of the Take Shore and Michigan Southern, roports one stecl sheet in the shell of the boiler to have cracked or broken in the way common to iron sheets in such cases, caused by imperfect construction or form of the boiler, Mr. Howard Fry, of the Phdadelphia and Erie road, reports five steel sheets in the shell of boilera on that road to have cracked during the year 1876, hut that in cvery case it was believed to he the result of bad pt Bela or bad design in the form and bracing of tho boiler, and not From tho quality of the steel. Your coimmittee believe that the material in the shell of the boilers should be heavier than that in gencral use: that a greater stiffness and surplus of strength would add greatly to the meee of time that they can ordinarily be used with safety, and lessen the eost of keeping them in repair from year to year, As the elastic limit of stec]l such as uscd in hoilers is not much, if any, abovo that of iron, the same thickness of atecl should be adopted asin the case of iron, notwithstandiug its superior toughness. It is important that Thoilaes should be so formed and stayed that with the highest pressure carried no art of one will change its original shape in the i hy reason of the pressuro. A ehange in shape in one direction by pressure, and returning again to its original position when the pressure is released, wd! soonor or later result in a erack. The same is true when braces are attached in such a way that the sheet is drawn from its true position hy the strains from the brace, In designing and constructing boilers, these matters should always receive the most careful atteution. Those .who have had much experience, and have given the matter close attcution, give it as their opinion that steel, being more compact than iron, is less liable to waste away from cor~ rosion, and in that rospect is to be preferred. From the expressions made to your committe, we find that steel is rapidly taking the place of iron for the shell of the hoiler. The Protection of Cars Against Lightning. The following is from Spang’s “Practical Treatise on Lightning Protection,” a work recently published hy Claxton, Remsen & Haifelfinger, of Philadelphia: A locomotive, with its escaping smoke and steam, moving or at rest, in a thunderstorm, will also invite a lightning discharge, and the liability of damage thereto depends upon the quantity of water that has fallen previous to the discharge, the electrical connection made by the rails with the road-bed, the conducting nature of the road-bed and the earth beneath it; also whether iron cars are in the train. When a number of iron ears, like those used in the transportation of petrolewun, are in a railway train, a lightning discharge will he diffused over them and greatly weakened, and therehy lessen the liahility of damage to, or ignition of, the contents thereof. But in the ease of a wooden car, the discharge will invariably pass through its interior and over nunates or contents in order to reach the earth, the contents heing generally a path of much better conductivity than the wooden hody of the car. Tho liability of injury or death of passengers and live-stock, and the ignition of powder or other comhustible material by lightning can be greatly lessened hy providing two metallic paths (one near each end) hetween the metal roof and the pedestals, axles and wheels of each wooden car used for their transportation. This can be done at a small expense hy applying Hat iron hars, two inches wide and one-eighth of an inch thick or four inches wide and one-sixteenth of an inch thick, along one of the sides and bottom of the hody of the car, and connecting them with the metal roof and center plates attached tothe hody, and also metallically connecting the center plates of the trucks with the nearest or most convenient metal rod or har commuuicating with the pedestals, thereby forming eontinuous metallie paths from the metal roof to the center plates, thence to the pedestals, axles, wheels and rails to the earth. During the summer season the rails of a railway track do not constitute very good earth terminals for a lightning conductor, owing to the dry condition and poor condnctivity of the road-bed, which generally consists of broken stone or furnace cinder, MINING AND SCIENTIFIC PRESS. a foot or more iu depth, and their ee for diffusing a lightning discharge will depend rincipally upon the quantity of raiu that has fallen previous to the discharge and the conductivity of the road-bed and the earth beneath. gy Orv Rams ror Nain Maxcracture.—aA manufacturer at Wheeling, West Virginia, is reported to be making a good quality of nails from old rails. Samyiles were some few days since showu at the otfice of the Wheeling /ntelligencer, part of which were made ont of rails, pure and siuple, and part ont of three parts rails and one part muck. hey are pronouuced good and are smooth and tough and drive well. This process of making uads, we learn, avoids the process of boiling iron, The rails are cut and piled for the heating furnaces, like so wnelt muck bar, and by the use of a thix in the heating process, are welded and made as malleable, ductile and close-textured in the sheet rolls as sa much piled muck. Nail plate is thus made $5.25 per ton cheaper than out of pigiron which has first been made into muck bar. This saving, says tho /nfelliyencer, is of itself a big protit, and will, if snecessful, revolutionize the old method. No mill can afford to puddle irou when by using this flux, old rails or pig iron can bo converted directly iuto nail plate. The same ae says, also: ‘We lately mentioned that Colonol Powell is making uails at the Belleville mill ont of the old rails and oneeighth muck iron, and that he claims to have an advantage equal to $13 per ton for pig metal. If this turns ont to be the case, the furnaces will not have nich to do for some time to come, inasmuch as it is estimated that there are enough old rads in the country to run all the tills for several years.” Russian Sm Raisrye.—At_ the RussianAmerican india-rnbher factory in St. Petersburg, Russia, a specialty is made of tho manufacture of air bags for raising sunken vessels. These bags are generally of a cylindrical form with rounded extremities, about 18 feet in length, 11 feet in diameter, with a eapacity of some 600 enbic feet, aud each bag can, itis calculated, raise a weight of 60 tons, although they are only guaranteed to lift 50. The bags are made of three thicknesses of coarse canvas, thoroughly impregnated and saturated with indea-rubber, and having also layers of the latter material iuterposed. The valves, ete., are of copper, and the bag is protected by a coarse net, its weight when fully furnished being very nearly 1,000 pounds. Without valves, cordage, chaius for attaching it to the object to be raised, euch a bag costs about $1,780, but when provided with all these appliances its price is raised to $2,720. Last ycar various experiments were made at Portsmouth, England, with these air bags, which were prezented tothe English Admiralty by the Russian government, and the Oberon was, after one or two attempts, successfully floated by means of them. A Raiuway PILe-pRIver.—A pile driver in nse in Nebraska is thus described: The engine, hammers, derrick, ladders, ete., and hoisting apparatus are all contined within an ordinary sized freight car. Heavy timber and beams make a strong frame-work for the foundation of the bed of the car. Itis huilt ona circular turntable which is worked on tbe car, and it can he turned either way, the pile-driver reaching out 20 feet beyond the width of the track. Piling for bridges can be driven on end or side of the track simply by shifting the box of the ear around. ‘The machinery is placed within in the most compact and convenient form possihle, and embraces all the modern improvements in the latest improved pile-drivers. It works with unusual rapidity, and itis but the work of a moment to attach it to an engine or train. 1ron SHIP-BUILDING IN THE Unrtep Srares.— According to a statement recently placed at the disposal of the New York Tribune hy the Register of the Treasury, there have been built in the United States, since 1866, for American owners, 251 iron vessels of all sizes, having a total measurement of 197,500 tons, About 150 were vessels of good size, They rank as follows: Less than 100 tons, 57; from 100 to 500 tons, 73; from 500 to 1,000 tons, 41; from 1,000 to 2,000 tons, 61; from 2,000 to 3,000 tons, 9; from 3,000 to4,000 tons, 8; over 5,000 tons, 2; total 251. SmokEeLESS Foryace.—We learn from an English exchange that Erskine’s patent smokeless furnace is au invention, the novelty of which consists of pecnliarly constructed firebars, resting directly upon tubes arranged in such a manner that heated air is admitted into the furnace in such proportions as to secure combustion of the gases before the smoke is actually made; it is so arranged that the air passing under the fire, and returning through the tuhes, isso greatly heated as to generate steam quickly and give a steadier supply. The bars also afford more air space, which is said to secure entire consumption of the fuel, and to greatly economize the same. Repvucine TH“ Propuction or Tin Piare.— We read in the Colliery Guardian that the owners of upwards of 100 mills have been prevailed upon to reduce the make of hoxes, the Association of Masters having agreed to close their works one week in every three weeks till . the end of the present year, a document having been signed to that effect. A fine of £500 will] he enforced against any parties who may violate the conditions of the agreement, i Ge S cleNTiFic ‘P ROGRESS. ud) who The Shell Mounds. Various theories have been suggested to furuish n key to the design and motive which led to the building of the shell mounds which are abundant on this coast, The latest raison etre is described by Mr. C. Mason Kinuc, Secretary of the San Francisco Microscopical Society, who has given much thought and inquiry to the subject. He writes: A vast deal of theorizing has been entered into for years past regarding these shell-mounds; as to how they were built, for what purpose and by whom. The last is by common consent conceded to the aboriginal races of red men, and perhaps the proccss and purpose can be made clear by observing what is going on to-day among the tribes of Indians in the Northwestern country and along Puget sound. . have given the matter some attentiou and, whenevor opportunity has permitted, have made iuquiries regarding the habits of the existing aborigines. From reliable parties long resident in that neighborhood, notably of whom is Mr. Edward Mdler, a gentleman who is a close observer of nature, J learn that it is the custom of the native dwellers of the forest to pitch their wigwams, built in the shape of a wooden structure some hundreds of feet in length and proportionately wide, formed of shakes or slabs 30 feet long, three to four inches wide and about two inches thick, which they split out of trees straight grained and clean Tiven—near to some spot where they find a bed of shell-fish and other couveniences. Sometimes as many as 100 occupants live in a single wigwam, which is divided into stalls or small rooms, Here they live year after year, throwing ont of the doors aud openings for windows their refuse in the shape of fish-bones, stones for heating water and the shells of clams, mussels and oysters. When the heap ontside becomes so great that a rampart, so to speak, is formed about them that becomes tronblesome to surmount, they level off a spot and move their dwelling, filling up the depression with the same debris, and so go on, year after year, When a chief dies, they bury him in the mound, which is at once a monumeut to their appetites and his sepuleber, and migrate to a spot miles away and do not return for 10 years, When other members of the chief’s family die, they are sometimes buried with them. ‘The chief usually lives to a ripe old age, wbich accounts for the fact that the teeth are most always found worn down to the gums. A skeleton recently unearthed from a mound near a new mill at West Berkeley, by Mr. Schnssler, was provided with a large jaw-hone and teeth worn down in a similar manner to the oue taken from the mound near Fillmore street, and now in the Alta office iu San Francisco. The supposition that these mounds were raised for some religious rites or purposes seems hardly tenable, reasoning from the fact of the known laziness of the primeval man, and the theory that the shells were brought from a great distance to where we now find the mounds is not necessary to account for their inland position any more than it wonld be to claim that the round boulders and sedimentary deposits of lakes and oceans which have long since sought other levels from the upheavals of their beds, were carted to their present geological position by some Titanic nation of the past. These shell-monnds cannot rank in interest with the artificial elevations of earth of the munnd-builders of the West, which, no doubt, were built for a purpose, and are not the refnse heaps of people whose only aim is to get along with as little exertion of mind or hody as is consistent with the aphorism that they live to eat and eat to live. The Analysis of the Diamond. Lavoisier, the great French chemist, undertook the examination of the diamond (Prof. Roscoe remarks), and it is worth while noticing how carefully he went to work—how he proceeded slowly from one step to another in the logical sequence until he arrived at the true solution of the question which he had undertaken to investigate—that is, until he was able to tell exactly what happens when the diamond evaporates in the fire, and why it did not dogo when surrounded with charcoal. In the first place, he evaporated the diamond by means of the hurning-glass, and he ohserved that no visihle vapor or smoke was given off, but that the diamond disappeared. He thought that perhaps the solid diamond had in some way heen dissolved hy the water, and that hy evaporating the water which was in the lower part of the belljar in which he hurnt the diamond he might ohtain the constituents of the diamond, in a solid form; but he found that no solid residue was left on evaporation, and thus no trace of the diamond could be found. His next experiment was that of placing a diamond in a focus of a less powerful lens than the one he had formerly used, so that tbe diamond was not heated to so high a temperature as before, again placing it however, in a bell-jar over water. He then found that the diamond, when not heated quite so strongly, lost only ahout one-quarter of its weight; it did not disappear altogether, but thie remarkable fact was noticed that it becamc eovered with a black substance, which Lavoisier descrihes as being exactly like lampblack or soot, so that it dirtied his lingers when touched, and made a black mark upon paper. Hence heconeluded that the diamond is susceptible of beiug brought, under certain circumstances, into the condition of charcoal, so that it really helongs to the class of comhustible bodies. He was, however, yet far from having proved this point, and he went on experimenting. He next measured the volume of airin which he was going to burn the diamond, and found it about eight eubic inches. Then he burned the diamond in this volume of air by means of a lens, and found that the air had diminished to a volume of six cubic inches, thus showing that the air had undergone some change by tho combustion of tbe diamond, and that two ont of eight volnmes of air had disappeared. The next experiment he rade was to examine the condition of the air in whieh the diamond had heeu evaporated. What changes had gone on in the air in consequence of the evaporation of the diamond? After allowing the glass in which he had burned the diamond to stand for four days, he poured clear lime-water into the jar in which the diamond lad been evaporated, and he says this lime-water was at once precipitated, in the same manner as if it had been brought into contact with gas evolved into effervescence and fermentatiou, or that giveu off in cases of metallic reduetion. Here, then, he had got on the track of what he wanted. Hitherto the diamond had apparently disappeared, and nothing was found to account for its disappearance; but now he had fonnd that there was something contained in the air in which the diamond was burned which was not contained in theair before. The next step he took was to examine the white precipitate or powder which formed, and he found that the substance thus precipitated from linewater by the air in which the diamond had been evaporated effervesced on treatment with acid, and evolved what was then known as fixed air, but which we now know as carbonic acid gas. Here, then, in his last experiment, he completes his proof, showing that exactly the same effects are observed when charcoal is experimented upon instead of diamond. Lavoisier had now run his quarry to earth; he had determined exactly what it is that is formed when a diamoud is burned. He has shown that a diamond, when byrned, produces exactly the same substance that is produced when common charcoal is burned, and he, therefore, legitimately coneludes that the diamond is only another form of the element carbon. The reason that the diamond did not burn in the furnace when snrrounded by a mass of charcoal was that the air, or rather the oxygen of the air, could not get to the diamond, because it was kept off by the charcoal, whieh hurned instead of the diamond. Evectric Phant.—The Gazette Horticole de Nicaragua publishes some information respecting a plant of the family of phytolaccas, which grows in that country and which possesses electro-magnetic properties. When a branch is cut off, the hand holding it experiences an electrie sensation similar to that from a Ruhmkorff battery, and the electrical influence of the plant has been observed several paces from the plant by the deviation of the needle of a small compass. When the compass was placed by the experimenter elose to the plants, the needle turned completely round. The soil is said by the Moniteur Industriel to contain no trace of iron or other magnetic metal, so that the property is inherent in the plantitself. The intensity of the phenomenon varies with the hour of the day—at night it is almost n7/, and most intense during the two midday hours or in a wind; during rain it was weak. No birds or insects have heen seen to rest upon the Phytolacea electriva, Curious PuHENoMENon or Heat. —M. J. Ohvier reports the following experiment: A square bar of steel, ahout 15 millimeters thick, and ahout 70 to 80 mm. long, is grasped firmly hy the operator, one hand heing placed at the center of the har and the other at the end. The free extremity is pressed strongly against a rapidly revolving emery wheel. Ina few minutes the ruhhed extremity hecomes hot, the hand at the center of the bar feels no heat, hut the hand atthe remote extremity hecomes so hot that the operator is ohliged to loosen it. WEAYTIER AND MAGNETISM.—Father Secchi, writing to a friend in Belgium, alludesin striking terms to the remarkable connection hetween the magnetism of the earth and the changes of the weather. He says that the variations shown hy the magnetic instruments are themselves sufficient to indicate the state of the sky. Even where there is no great movement of the barometer, following such magnetic disturbances, tbere are, especially in summer, changes of the wind and sometimes storms. Discovery or Native Mercory.—M. Leymerie, in the Chemical News, writes: In the Domairie du Cros, situated in a glen opening directly into the valley of the Herault, the decayed roots of a mulberry tree were being dug up, On breaking one of thei there issued from it a wave of merenry. The eountry people are of opinion that the deatb of certain mulherry trees is due to the action of mercury. The soil is of a schistous nature.

19 July 14, 1877.] ay? Ke M ECHANICAL Pp ROGRESS. faa tal was Steel Locomotive Boilers. One of the topics under consideration at the late meeting of railway inaster mechanies, at Cleveland, was the relative quality of trou and steel as material for railroad boilers. The testimony was almost unswerving in favor of steel as the best material for the shell of the boiler. We quote from a report of n conmittee as follows: With two exceptions all express themselves decidedly in favor of steel for the shell of the boiler. It is superior to iron in strength, and less ditheult to shape and put together, and seems to be in every way preferable. Those who have nsed it most extensively for this purpose are the most decided in preferring it. Not a single instance is reported where stcel in the shell of a boiler has ruptured when cold, or in heating up, or from putting cold water im the boder while hot, as so frequently occnrs in the case of the sheets of tho tiro-box. Mr. Sedgley, of the Take Shore and Michigan Southern, roports one stecl sheet in the shell of the boiler to have cracked or broken in the way common to iron sheets in such cases, caused by imperfect construction or form of the boiler, Mr. Howard Fry, of the Phdadelphia and Erie road, reports five steel sheets in the shell of boilera on that road to have cracked during the year 1876, hut that in cvery case it was believed to he the result of bad pt Bela or bad design in the form and bracing of tho boiler, and not From tho quality of the steel. Your coimmittee believe that the material in the shell of the boilers should be heavier than that in gencral use: that a greater stiffness and surplus of strength would add greatly to the meee of time that they can ordinarily be used with safety, and lessen the eost of keeping them in repair from year to year, As the elastic limit of stec]l such as uscd in hoilers is not much, if any, abovo that of iron, the same thickness of atecl should be adopted asin the case of iron, notwithstandiug its superior toughness. It is important that Thoilaes should be so formed and stayed that with the highest pressure carried no art of one will change its original shape in the i hy reason of the pressuro. A ehange in shape in one direction by pressure, and returning again to its original position when the pressure is released, wd! soonor or later result in a erack. The same is true when braces are attached in such a way that the sheet is drawn from its true position hy the strains from the brace, In designing and constructing boilers, these matters should always receive the most careful atteution. Those .who have had much experience, and have given the matter close attcution, give it as their opinion that steel, being more compact than iron, is less liable to waste away from cor~ rosion, and in that rospect is to be preferred. From the expressions made to your committe, we find that steel is rapidly taking the place of iron for the shell of the hoiler. The Protection of Cars Against Lightning. The following is from Spang’s “Practical Treatise on Lightning Protection,” a work recently published hy Claxton, Remsen & Haifelfinger, of Philadelphia: A locomotive, with its escaping smoke and steam, moving or at rest, in a thunderstorm, will also invite a lightning discharge, and the liability of damage thereto depends upon the quantity of water that has fallen previous to the discharge, the electrical connection made by the rails with the road-bed, the conducting nature of the road-bed and the earth beneath it; also whether iron cars are in the train. When a number of iron ears, like those used in the transportation of petrolewun, are in a railway train, a lightning discharge will he diffused over them and greatly weakened, and therehy lessen the liahility of damage to, or ignition of, the contents thereof. But in the ease of a wooden car, the discharge will invariably pass through its interior and over nunates or contents in order to reach the earth, the contents heing generally a path of much better conductivity than the wooden hody of the car. Tho liability of injury or death of passengers and live-stock, and the ignition of powder or other comhustible material by lightning can be greatly lessened hy providing two metallic paths (one near each end) hetween the metal roof and the pedestals, axles and wheels of each wooden car used for their transportation. This can be done at a small expense hy applying Hat iron hars, two inches wide and one-eighth of an inch thick or four inches wide and one-sixteenth of an inch thick, along one of the sides and bottom of the hody of the car, and connecting them with the metal roof and center plates attached tothe hody, and also metallically connecting the center plates of the trucks with the nearest or most convenient metal rod or har commuuicating with the pedestals, thereby forming eontinuous metallie paths from the metal roof to the center plates, thence to the pedestals, axles, wheels and rails to the earth. During the summer season the rails of a railway track do not constitute very good earth terminals for a lightning conductor, owing to the dry condition and poor condnctivity of the road-bed, which generally consists of broken stone or furnace cinder, MINING AND SCIENTIFIC PRESS. a foot or more iu depth, and their ee for diffusing a lightning discharge will depend rincipally upon the quantity of raiu that has fallen previous to the discharge and the conductivity of the road-bed and the earth beneath. gy Orv Rams ror Nain Maxcracture.—aA manufacturer at Wheeling, West Virginia, is reported to be making a good quality of nails from old rails. Samyiles were some few days since showu at the otfice of the Wheeling /ntelligencer, part of which were made ont of rails, pure and siuple, and part ont of three parts rails and one part muck. hey are pronouuced good and are smooth and tough and drive well. This process of making uads, we learn, avoids the process of boiling iron, The rails are cut and piled for the heating furnaces, like so wnelt muck bar, and by the use of a thix in the heating process, are welded and made as malleable, ductile and close-textured in the sheet rolls as sa much piled muck. Nail plate is thus made $5.25 per ton cheaper than out of pigiron which has first been made into muck bar. This saving, says tho /nfelliyencer, is of itself a big protit, and will, if snecessful, revolutionize the old method. No mill can afford to puddle irou when by using this flux, old rails or pig iron can bo converted directly iuto nail plate. The same ae says, also: ‘We lately mentioned that Colonol Powell is making uails at the Belleville mill ont of the old rails and oneeighth muck iron, and that he claims to have an advantage equal to $13 per ton for pig metal. If this turns ont to be the case, the furnaces will not have nich to do for some time to come, inasmuch as it is estimated that there are enough old rads in the country to run all the tills for several years.” Russian Sm Raisrye.—At_ the RussianAmerican india-rnbher factory in St. Petersburg, Russia, a specialty is made of tho manufacture of air bags for raising sunken vessels. These bags are generally of a cylindrical form with rounded extremities, about 18 feet in length, 11 feet in diameter, with a eapacity of some 600 enbic feet, aud each bag can, itis calculated, raise a weight of 60 tons, although they are only guaranteed to lift 50. The bags are made of three thicknesses of coarse canvas, thoroughly impregnated and saturated with indea-rubber, and having also layers of the latter material iuterposed. The valves, ete., are of copper, and the bag is protected by a coarse net, its weight when fully furnished being very nearly 1,000 pounds. Without valves, cordage, chaius for attaching it to the object to be raised, euch a bag costs about $1,780, but when provided with all these appliances its price is raised to $2,720. Last ycar various experiments were made at Portsmouth, England, with these air bags, which were prezented tothe English Admiralty by the Russian government, and the Oberon was, after one or two attempts, successfully floated by means of them. A Raiuway PILe-pRIver.—A pile driver in nse in Nebraska is thus described: The engine, hammers, derrick, ladders, ete., and hoisting apparatus are all contined within an ordinary sized freight car. Heavy timber and beams make a strong frame-work for the foundation of the bed of the car. Itis huilt ona circular turntable which is worked on tbe car, and it can he turned either way, the pile-driver reaching out 20 feet beyond the width of the track. Piling for bridges can be driven on end or side of the track simply by shifting the box of the ear around. ‘The machinery is placed within in the most compact and convenient form possihle, and embraces all the modern improvements in the latest improved pile-drivers. It works with unusual rapidity, and itis but the work of a moment to attach it to an engine or train. 1ron SHIP-BUILDING IN THE Unrtep Srares.— According to a statement recently placed at the disposal of the New York Tribune hy the Register of the Treasury, there have been built in the United States, since 1866, for American owners, 251 iron vessels of all sizes, having a total measurement of 197,500 tons, About 150 were vessels of good size, They rank as follows: Less than 100 tons, 57; from 100 to 500 tons, 73; from 500 to 1,000 tons, 41; from 1,000 to 2,000 tons, 61; from 2,000 to 3,000 tons, 9; from 3,000 to4,000 tons, 8; over 5,000 tons, 2; total 251. SmokEeLESS Foryace.—We learn from an English exchange that Erskine’s patent smokeless furnace is au invention, the novelty of which consists of pecnliarly constructed firebars, resting directly upon tubes arranged in such a manner that heated air is admitted into the furnace in such proportions as to secure combustion of the gases before the smoke is actually made; it is so arranged that the air passing under the fire, and returning through the tuhes, isso greatly heated as to generate steam quickly and give a steadier supply. The bars also afford more air space, which is said to secure entire consumption of the fuel, and to greatly economize the same.

Repvucine TH“ Propuction or Tin Piare.— We read in the Colliery Guardian that the owners of upwards of 100 mills have been prevailed upon to reduce the make of hoxes, the Association of Masters having agreed to close their works one week in every three weeks till . the end of the present year, a document having been signed to that effect. A fine of £500 will] he enforced against any parties who may violate the conditions of the agreement, i Ge S cleNTiFic ‘P ROGRESS. ud) who The Shell Mounds. Various theories have been suggested to furuish n key to the design and motive which led to the building of the shell mounds which are abundant on this coast, The latest raison etre is described by Mr. C. Mason Kinuc, Secretary of the San Francisco Microscopical Society, who has given much thought and inquiry to the subject. He writes: A vast deal of theorizing has been entered into for years past regarding these shell-mounds; as to how they were built, for what purpose and by whom. The last is by common consent conceded to the aboriginal races of red men, and perhaps the proccss and purpose can be made clear by observing what is going on to-day among the tribes of Indians in the Northwestern country and along Puget sound. . have given the matter some attentiou and, whenevor opportunity has permitted, have made iuquiries regarding the habits of the existing aborigines. From reliable parties long resident in that neighborhood, notably of whom is Mr. Edward Mdler, a gentleman who is a close observer of nature, J learn that it is the custom of the native dwellers of the forest to pitch their wigwams, built in the shape of a wooden structure some hundreds of feet in length and proportionately wide, formed of shakes or slabs 30 feet long, three to four inches wide and about two inches thick, which they split out of trees straight grained and clean Tiven—near to some spot where they find a bed of shell-fish and other couveniences. Sometimes as many as 100 occupants live in a single wigwam, which is divided into stalls or small rooms, Here they live year after year, throwing ont of the doors aud openings for windows their refuse in the shape of fish-bones, stones for heating water and the shells of clams, mussels and oysters. When the heap ontside becomes so great that a rampart, so to speak, is formed about them that becomes tronblesome to surmount, they level off a spot and move their dwelling, filling up the depression with the same debris, and so go on, year after year, When a chief dies, they bury him in the mound, which is at once a monumeut to their appetites and his sepuleber, and migrate to a spot miles away and do not return for 10 years, When other members of the chief’s family die, they are sometimes buried with them. ‘The chief usually lives to a ripe old age, wbich accounts for the fact that the teeth are most always found worn down to the gums. A skeleton recently unearthed from a mound near a new mill at West Berkeley, by Mr. Schnssler, was provided with a large jaw-hone and teeth worn down in a similar manner to the oue taken from the mound near Fillmore street, and now in the Alta office iu San Francisco. The supposition that these mounds were raised for some religious rites or purposes seems hardly tenable, reasoning from the fact of the known laziness of the primeval man, and the theory that the shells were brought from a great distance to where we now find the mounds is not necessary to account for their inland position any more than it wonld be to claim that the round boulders and sedimentary deposits of lakes and oceans which have long since sought other levels from the upheavals of their beds, were carted to their present geological position by some Titanic nation of the past. These shell-monnds cannot rank in interest with the artificial elevations of earth of the munnd-builders of the West, which, no doubt, were built for a purpose, and are not the refnse heaps of people whose only aim is to get along with as little exertion of mind or hody as is consistent with the aphorism that they live to eat and eat to live. The Analysis of the Diamond. Lavoisier, the great French chemist, undertook the examination of the diamond (Prof. Roscoe remarks), and it is worth while noticing how carefully he went to work—how he proceeded slowly from one step to another in the logical sequence until he arrived at the true solution of the question which he had undertaken to investigate—that is, until he was able to tell exactly what happens when the diamond evaporates in the fire, and why it did not dogo when surrounded with charcoal. In the first place, he evaporated the diamond by means of the hurning-glass, and he ohserved that no visihle vapor or smoke was given off, but that the diamond disappeared. He thought that perhaps the solid diamond had in some way heen dissolved hy the water, and that hy evaporating the water which was in the lower part of the belljar in which he hurnt the diamond he might ohtain the constituents of the diamond, in a solid form; but he found that no solid residue was left on evaporation, and thus no trace of the diamond could be found. His next experiment was that of placing a diamond in a focus of a less powerful lens than the one he had formerly used, so that tbe diamond was not heated to so high a temperature as before, again placing it however, in a bell-jar over water. He then found that the diamond, when not heated quite so strongly, lost only ahout one-quarter of its weight; it did not disappear altogether, but thie remarkable fact was noticed that it becamc eovered with a black substance, which Lavoisier descrihes as being exactly like lampblack or soot, so that it dirtied his lingers when touched, and made a black mark upon paper. Hence heconeluded that the diamond is susceptible of beiug brought, under certain circumstances, into the condition of charcoal, so that it really helongs to the class of comhustible bodies. He was, however, yet far from having proved this point, and he went on experimenting. He next measured the volume of airin which he was going to burn the diamond, and found it about eight eubic inches. Then he burned the diamond in this volume of air by means of a lens, and found that the air had diminished to a volume of six cubic inches, thus showing that the air had undergone some change by tho combustion of tbe diamond, and that two ont of eight volnmes of air had disappeared. The next experiment he rade was to examine the condition of the air in whieh the diamond had heeu evaporated. What changes had gone on in the air in consequence of the evaporation of the diamond? After allowing the glass in which he had burned the diamond to stand for four days, he poured clear lime-water into the jar in which the diamond lad been evaporated, and he says this lime-water was at once precipitated, in the same manner as if it had been brought into contact with gas evolved into effervescence and fermentatiou, or that giveu off in cases of metallic reduetion. Here, then, he had got on the track of what he wanted. Hitherto the diamond had apparently disappeared, and nothing was found to account for its disappearance; but now he had fonnd that there was something contained in the air in which the diamond was burned which was not contained in theair before. The next step he took was to examine the white precipitate or powder which formed, and he found that the substance thus precipitated from linewater by the air in which the diamond had been evaporated effervesced on treatment with acid, and evolved what was then known as fixed air, but which we now know as carbonic acid gas. Here, then, in his last experiment, he completes his proof, showing that exactly the same effects are observed when charcoal is experimented upon instead of diamond. Lavoisier had now run his quarry to earth; he had determined exactly what it is that is formed when a diamoud is burned. He has shown that a diamond, when byrned, produces exactly the same substance that is produced when common charcoal is burned, and he, therefore, legitimately coneludes that the diamond is only another form of the element carbon. The reason that the diamond did not burn in the furnace when snrrounded by a mass of charcoal was that the air, or rather the oxygen of the air, could not get to the diamond, because it was kept off by the charcoal, whieh hurned instead of the diamond. Evectric Phant.—The Gazette Horticole de Nicaragua publishes some information respecting a plant of the family of phytolaccas, which grows in that country and which possesses electro-magnetic properties. When a branch is cut off, the hand holding it experiences an electrie sensation similar to that from a Ruhmkorff battery, and the electrical influence of the plant has been observed several paces from the plant by the deviation of the needle of a small compass. When the compass was placed by the experimenter elose to the plants, the needle turned completely round. The soil is said by the Moniteur Industriel to contain no trace of iron or other magnetic metal, so that the property is inherent in the plantitself. The intensity of the phenomenon varies with the hour of the day—at night it is almost n7/, and most intense during the two midday hours or in a wind; during rain it was weak. No birds or insects have heen seen to rest upon the Phytolacea electriva, Curious PuHENoMENon or Heat. —M. J. Ohvier reports the following experiment: A square bar of steel, ahout 15 millimeters thick, and ahout 70 to 80 mm. long, is grasped firmly hy the operator, one hand heing placed at the center of the har and the other at the end. The free extremity is pressed strongly against a rapidly revolving emery wheel. Ina few minutes the ruhhed extremity hecomes hot, the hand at the center of the bar feels no heat, hut the hand atthe remote extremity hecomes so hot that the operator is ohliged to loosen it. WEAYTIER AND MAGNETISM.—Father Secchi, writing to a friend in Belgium, alludesin striking terms to the remarkable connection hetween the magnetism of the earth and the changes of the weather. He says that the variations shown hy the magnetic instruments are themselves sufficient to indicate the state of the sky. Even where there is no great movement of the barometer, following such magnetic disturbances, tbere are, especially in summer, changes of the wind and sometimes storms. Discovery or Native Mercory.—M. Leymerie, in the Chemical News, writes: In the Domairie du Cros, situated in a glen opening directly into the valley of the Herault, the decayed roots of a mulberry tree were being dug up, On breaking one of thei there issued from it a wave of merenry. The eountry people are of opinion that the deatb of certain mulherry trees is due to the action of mercury. The soil is of a schistous nature.