A PAPER READ BEFORE THE MIDLAND SCIENTIFIC SOCIETY, ENGLAND, BY A LUPTON, F.G.S In instituting the experiments, the result of which I propose to describe to the present meeting, and which extended over a period of a year and a half, I was actuated by a desire to ascertain the amount of iruth in the oftenrepeated statements of practical men, that the temperature of deep mines that had been at work for some time, did not exceed the temperature of shallower mines, and to reconcile, if possible, those statements with the generallyaccepted observations recorded by scientific men, which tended to prove a gradual increase in the earth's temperature in descending Owing to the kindness of the engineer, I had the opportunity of ascertaining the temperature of two shafts as they were sunk ; the method of observation was as follows : A borehole was made in the center of the shaft bottom, from 6 to 9 feet deep ; a thermometer was let into the borehole by means of a wire, then the top of the hole was tightly plugged with hemp and clay, in order to prevent, as far as possible, the circulation of water in the hole The thermometer was allowed to remain in the hole for 24 hours at a time I used maximum registering thermometers, some by Negretti Zambra, and some by Mr Davis, of Derby Owing to the presence of water in both the shafts, the value of these experiments is much diminished ; and, in one shaft, which attained a depth of 906 feet, the rise in temperature, as recorded by the thermometers, was only 1 for every 120 feet; in the other shaft, where there was less water, and which attained a depth of 966 feet, the rise in temperature was 1 in 73 feet I next had a series of holes bored horizontally in the shaft sides, into each of which I put a thermometer ; the holes were tightly plugged, to hinder the circulation of air in them The temperature of these holes re mained the same, winter and summer, throughout great variations of temperature in the air of the shaft In the drier of the two shafts abovenamed the rate of increase in temperature varied from 1 in 70 feet, to 1 in 60 feet I then repeated similar experiments to these last at the Hucknall Colliery, in Nottinghamshire, through the kindness of Mr Fowler, the engineer, and found a regular increase in the temperature of the works of 1 in 60 feet; the depth of the pit is 1,250 feet Also, by the kind permission of Mr E Hedley, the engineer, I took the temperature of the coal at the bottom of the Annesley Colliery; the temperature was 73, and the depth 1,425 feet, being an increase of 1 in 60 feet By the kindness of Mr Carrington, I was enabled to make similar observations at the Kineton Park Colliery; the pit is 1,200 feet deep, the temperature of the coal 71, being an increase of 1 in 55 feet The result of all my observations is, that the permanent temperature of the earth, at the depth of 50 feet, is 50, and the regular rate of increase in temperature, below that depth, 1 in 60 feet Observations made by others in the North of England and South Wales seem to prove the temperature of the mines depends on the depth below the surface of the ground, irrespective of the depth below the sealevel The next question is, given the above rate of increase in the earth's temperature, at what depths will it be practicable to get coal ? I, therefore, made some experiments to ascertain what effect ventilation would have in cooling the mines At the Hucknall Colliery the temperature of the coal, when first the pit was sunk was 70; ten months afterward a hole was bored, 2 feet deep, into the side of a coal head, through which a current of air had passed, and the temperature of the coal was found to be 591 At the Annesley Colliery, the coal, when first cut, had a temperature of 73, whilst a borehole in a head that had been driven six months, had a temperature of 64 At Kineton Park, the coal, when first cut, had a temperature of 73; and, after three months exposure to a current of cold air, the temperature of the coal in a hole 2 feet deep was 60 Many other experiments, at other collieries, gave similar results With a small sensitive thermometer I found the coal, in heads that had been driven some time, was, at a depth of only 6 inches from the surface, of the same temperature as the air circulating past From the above experiments I came to the conclusion that the passages in a mine were soon cooled by a brisk current of air, coal being a bad conductor of heat The internal heat of the pillars of coal could not be conveyed to the surface as quickly as it is carried away by the current of air At a depth of 10,000 feet, the temperature of the coal would probably be about 212 According to Peilet, 1 square foot of cast iron, at a temparature of 212, in an atmosphere at a temperature of 79, would give out a certain number of units of heat in a minute Supposing, for the sake of argument, that 1 square foot of coal surface would give out the same number of units of heat, under similar circumstances, I have calculated that a mine of sufficient extent to produce 1,000 tuns of coal per diem, in a seam of average thickness, would raise from 1,300,000 to 1,500,000 cubic feet of air in a minute, from a temperature of 59 to 79 In estimating the extent of the heating surface in the mine, I have taken the face of work at a temperature of 212; and the gateroads less than a year old have been reckoned as having, on the average, only half the heating power of freshly cut coal, and all the roads along which a current has been passing for more than a year, are' supposed to be cooled down to a temperature of 60 It is quite possible for men to work in a current of air no hotter than 79, and it is also an engineering possibility to produce a current of air of the abovementioned volume ; and the expense of producing such a current would probably not be an insurmountable obstacle Having considered the subject a great deal, I have come to the conclusion that, as far as the temperature of the earth is concerned, it will be possible to work coal at a depth of even 10,000 feet An Apparatus for Prognosticating the Weatlier The following iB the description of an instrument devised by M Bonneville, of Paris The instrument is composed of the motor, which imparts motion to the index needle Themotor is composed of two wooden strips, or thin blades, stuck one upon the other, of different hygrometric capacities, one of which is called the positive, and the other the negative These strips, or thin blades of wood, are curvilinear, and assume the form of an arc of a circle One of the extremities of this arc is fixed to a square held by screws on to a brass disk ; the other extremity is loose and movable It is connected by a silken thread passing round one of the two grooves of a pulley, with an arbor forming the axis of the index needle The force of the motor is opposed by a spring fixed upon the brass disk, and connected by another silken thread with the arbor, round the second groove of which it is wound The expansion of the motor, or its contraction as shown by the index, indicates the presence of much moisture in the air or the opposite condition _*a* IMPROVED MARINER'S COMPASSThe Earl of Caithness is the inventor of a new mode of suspending ships' compasses, which for efficiency and simplicity is said to surpass anything yet produced Instead of the two concentric brass rings having their axles at right angles, known as gimbals, Lord Caitk ness employs a pendulum and ball, which ball works in a socket in the center of the bottom of the compass bowl The compass works, therefore, on one bearing on the ballandsocket principle, and thus maintains its parallelism with the horizon in the heaviest weather If we may credit the published reports of the trials, the simplicity of this invention is not more striking than its efficiency It is stated that it has already stood the most trying tests, and the oscillation of coinpasses to which it is applied, as compared with the oscillation of the gimbal compass is as degrees to points 116 The " Sky Railway" in Running Order j A visitor to the White Mountains describes Mount Washington Railway,which ascends the mountain in a tolerably straight course, following the general lino of the old Fabyan bridle path Thcdepot is 2,685 feet above the level of the sea, or 1,117 feet above the White Mountain House This leaves a grade of 8,000 feet to be ov come, as the hight of the mountain is 6,285 feet above tlu level of the sea The length of the road | is two miles and thirteensixteenths The heaviest grade is thirteen inches to the yard, and the very lightest one inch to the foot A part of the course is over "Jacob's Ladder," the zizzag portion of the old bridle path lying just above the point where the trees are left behind The railroad takes a generally straight line, however, curving slightly, only to maintain a direct course The rolling stock is in a much better condition than it was last year There are two locomotives now in use, and a third is expected from the establishment of Mr Walter Aikcn, at Franklin, this week or next These are more powerful than those in use last year A new car has also been constructed The locomotive pushes the car before it up the incline, and both run upon three rails, the center one being a cog rail The engine and car are kept upon the track by friction rollers under the side of the cog rail, and the appliances for stopping the descent are ample By means of atmospheric brakes either the car or engine could be sent down alone at any given rate, fast or slow, and there are also hand brakes operating with equal directness upon the central wheels, together with other means of governing the machinery of locomotion Every competent person who has examined the road and the running machinery, pronounce both as safe as they could possibly be made The landing place at the top of the mountain is directly in the rear of the telegraph office, and but a lew rods from the door of the TipTop House We this week present our readers with a portrait of the late John A Roebling, whose obituary was published in our issue of Aug 7th It is well worth preserving as a souvenir of one of the most distinguished engineers of the age Improvement In Sadirons, This invention consists, mainly, in so constructing a sadiron that it may be constantly and uniformly heated by a gas r flame while in use The engraving is a perspective view of ; the device with a portion of the sadiron broken away to show ' the internal arrangement of the burners employed These i aro so plainly shown in the illustration that no further reference to them will be needful The sadiron has an interior chamber which may be called the combustion chamber, and an outer one completely surrounding the former, and inclosed by the exterior walls of the Sadiron Through these exterior walls are openings which admit air to feed the flame, and afford exit for the carbonic acid gas generated The wall immediately surrounding the inner chamber, called the flame wall has also openings communicating with the outer chamber, go that a fine flow of air can reach the burners, and the gases of com bustion escape through the passage between the flame wall and the exterior walls of the sadiron The position of the burners is such as to uniformly heat the iron particularly the bottom or smoothing surface, and they are readily lighted from openings provided for the purpose The gas is conveyed from an ordinary bracket ]gas burner, having a suitable framework attached to the wall for the support of two pulleys, one fixed and the other movable, the movable one descending by its own weight ; or if needful it may be weighted A flexible tube passes over these pulleys, and the moving one takes up the slack or lets it out as wanted,to adjust the length of the tube to the motions of the hand in smoothing linen Patented, June 15, 1869, by Andrew J Kennedy, of St Louis', Mo Address A J Kennedy, care of RRadke, 515 Olive street, St Louis, Mo The Hoosac Tunnel THE new contractors on the Hoosac Tunnel are pushing the work ahead quite rapidly During the month of June they drove the heading at the east end in 160 feet, and it is in now over a mile and an eighth The first week in July they made 30 feet and the next week 40 feet The first and second enlargements are also being pushed ahead vigorously They are having new drills made to operate on the roof, which they hope to have in operation in September, and by which they expect to increase their progress very materially They are also erecting buildings near the mouth of the tunnel for four additional compressors, so as to give them more power They will be run by steam They have now 200 men at work at the east end, divided in three gangs, who work night and day continuously, resting only from midnight Sat urday to midnight Monday The central shaft is down about i 700 feet, and is sunk at the rate of more than a foot a day , At the west end they have just got fairly at work, and they i expect to make over 100 feet a month j SSJlaelc upon Cotton by Dyeing The old fast black upon cotton was obtained by giving a blue ground with indigo, then galling and working in sul phate of iron, sometimes with addition of logwood ; alder bark, and other similar substances wero also employed ; and the goods usually finished in an emulsion of oil, to take off the harshness which iron mordants so generally communicate Later on, what was called the Manchester black, was obtained by first steeping in galls or sumac, then working in the copperas vat, and afterward in logwood containing some verdigris, and repeating these operations until the desired shade was obtained Galls are now scarcely ever used; sumac, which is cheaper, being employed in substitution ; and the processes, though almost infinite in details, consist essentially of steeping in sumac, then working in an iron bath, and afterward raising in logwood One method said to give good results, consists in steeping in sumac for twelve hours, then working through lime water and exposing to the air until the light green color at first produced passes to a dull heavy shade; the goods are then passed through a solution of green copperas, and exposed to i the air until they appeared black while in the wet state ; if! dried they would be found to be only gray or slate color To fill up the color the goods are passed into the logwood bath j (some authorities say it is advisable to pass them through ' lime water first) for a sufficient time ; lifted, some copperas : added and the goods raised in it; for light goods this suffices j to produce a black, heavier goods require a repetition of the processes A rapid continuous method of dyeing black on light goods is practiced in Lancashire ; the goods are passed through a decoction of catechu, then immediately into a solution of bichromate of potash, next into decoction of log wood, then into green copperas,, und lastly through u, decoction , of some red wood, as camwood or Brazil wood The order I of these liquids may be changed within certain limits, i A simpler method of dyeing hy means of bichromates is | also given, which consists in steeping the goods in logwood, I exposing them to the air and drying, then passing them into ! bichromate of potash neutralized by crystals of soda, by 1 which the logwood is " struck" of an intense black, and fixed Velveteens are dyed black by reiterated passages in logwood and green copperas until a dark brown is produced, then passed in sumac and sulphate of copper, with sometimes addition of peachwood or Brazil wood Fustic is an ingredient in all dyes where a brownish or jet black is desired Black is one of the most difficult colors to dye, and no one but a practical man understands the difficulties of obtaining regular and good results, especially when firstclass colors are aimed at It is useless to give weights and quantities when these are really only inferior elements of success ; a slight change in the quality of the sumac, some thing different in the " ageing " or " mastering " of the logwood, some slight modification in the tern perature and pressure of *he " stills" in which the liquors are made, and other causes not more conspicuous, have frequently in my experience put works almost to a stand still And when I have been called in for advice, it has been evident that chemistry could only give conjectures as to what was wrong Those failures in producing satisfactory colors would not be apparant to an unpracticed eye; the defects would only consist in those hues and reflections of shade being wanting which were most esteemed and usually produced Though it is exceedingly difficult in most cases to trace the actual cause^of inferior results, there have been in my practice very evident occasions in which a most trivial and apparently unimportant cause has produced very embarrassing effects ; the closest attention on the part of a foreman or manager is most essential in order that these things may be avoided, or if they occur that their cause may be i8covevQ\Di:tionary of Dyeing and Calico Printing ZK3 SJse of unotton In entistry This statement appears absurd at first, as if dentists used guncotton as an explosive agent; but the fact is, that quite recently the collodion made of guncotton, hardened by evaporation, as a varnish, into thin sheets, lias been used as a substitute for the objectionable vulcanized rubber, as a basis for support of false sets of teeth For this purpose different sheets are softened by ether, and pressed together in the mold, which is made in a way shiiiiur to that in use for making the platinum or indiarubber sols One of the objections to tlio vulcanized rubber sets of teeth is the dark color, which, can only be corrected by vermilion, wliieh gives it a reddish color, somewhat similar to that of the gums Vermilion, however, being a compound of mercury, seriously aiiects the health of some persons, whose peculiar constitution renders them very sensitive to the influences of this pernicious metal In drying, collodion contracts considerably, and the only additional trouble, in making objects of (hj collodion, is to make the molds larger, by repeated castings and recastings in plaster; the plaster ^expanding every time a little, the last mold obtained may "be sufficiently enlarged to compensate for the shrinkage of the material Sets of teeth made on collodion are much lighter and stronger than on any other material thus far employed for that purpose, and, no doubt, will soon come into general use in the United States, as the dentists of this country are among the most progressive in the worldDruggists' Circular TieSpotting Machine, This device is thus described by the Chicago Railway Mevicw : " Our readers are aware that rails are generally laid level upon the ties, with the result of bringing the whole weight of the car upon the inside of the rail and the inclined rolling surface of the wheel Mr Jauriet conceived the idea of laying the rail so as [ to incline inwards on the same level as the surface of the wheel The old hand process of doing this, with adze, is slow and unequal and costs more than it comes to The tiespotter, attached to a car and transported from place to place on the line, may be generally described as consisting of two vertical shafts, with knives attached, to which the ties are brought by means of a chain feed The knives are adjustable so as to 1 spot' at an angle, or in the ordinary manner The machine is operated by the engine attached, and requires, besides the engineer, six men to operate it, who do the work of from fifteen to twenty A recent experiment resulted in the spotting of seventysix ties in fifteen minutes" TELEGRAMS from various points seem to indicate that at least a majority of the astronomers have been in luck in witnessing the eclipse The weather was generally fine
This article was originally published with the title "On the Temperature of Coal Mines"