134 



POPULAR SCIENCE NEWS. 



[SErrKMBEH, 1S89. 



ever put together, but the excellent engraving 

 (which we copy froin La Nature) shows 

 that the whole secret consists in so cutting 

 them that they slide together cornerwise, and 

 not directly, as their appearance would indi- 

 cate. The upper figure shows an apparent 

 combination of two ditterent joints, — the sim- 

 ple tenon and the swallow-tail joint, — but, in 

 reality, it is only a double tenon. 



These examples are of special interest as 

 examples of the excellent work performed ))y 

 the pupils of the technical school at (irenoble, 

 and those of our Yankee readers who have 

 the traditional fondness for whittling may like 

 to try and see if they can perform the work 

 etiuallv well. 



AN AUTOMATIC RFCADING LAMP. 

 TuE latest and most ingenious application of tlie 

 penn^-in-the-slot automatic apparatus is the adapta- 

 tion of tliis principle to the supply of electric light 

 in the shape of reading lamps for railway carriages, 

 omnibuses, tramcars, etc. The lamp in question 

 has l5cen patented by a Leeds firm. The lamp, as 

 originally patented, consists of a clockwork appara- 

 tus, contained in a box sin. by ^in. and 3in. And 

 by introducing a penny into the top of the machine, 

 and subsequently pressing a knob, the mechanism 

 is set in motion, and an electric light obtained, 

 which, after burning for half an hour, is automati- 

 cally extinguished. The lamp can, moreover, be 

 extinguished at will, by pressing a second knob. 

 This lamp will, it is stated, be in use in the course 

 of a few days on the Great Western Railw.iy. The 

 lamps are lighted from an accumulator, which, 

 placed in any of the compartments of a carriage, 

 will supply with electricity the whole of the lamps 

 in the carriage. The accumulator can thus be 

 changed at any station without interfering with the 

 light. The accumulators will be charged with a 

 forty hours supply. A remarkable feature is that 

 should the supply of electricity fail, or should the 

 lamp fail to act, the coin deposited is automatically 

 returned to the operator. The lamps will be fixed 

 under the hat rail of the carriages, and, by this 

 means, passengers can, when leaning back, read at 

 their ease. — Mechanical World {Eng.) 



INDUSTRIAL MEMORANDA. 



TuK Watch Anatomizkd. — The average watch 

 is composed of 175 dilVerent pieces, comprising up- 

 wards of 2,400 separate and distinct operations in 

 its manufacture. The balance has 18,000 beats or 

 vibrations per hour, i2,ofx),aSo in thirty days, 

 157,680,000 in one year. It travels i 43-100 inches 

 with each vibration, which is equal to i)^ miles in 

 twenty-four hours, 2i)2''-i miles in thirty days, or 

 3.558^^4 miles in one year. 



Skinal LioiiTs FOR Ships and LuiHTHousEs.— 

 Jaksch proposes the following mixture for distress 

 signals: Barium nitrate, 30 parts; magnesium 

 powder, 20 parts; Hower of sulphur, 4 parts, and 

 beef tallow, 7 parts. The tallow is added in a 

 melted state, and the mixture sifted. This mass is 

 filled into strong zinc boxes 4 inches in height ;iiul 3 

 in diameter. It gives for 20 seconds a light of 20,000 

 candles, visible in clear air at the distance of 60 

 miles. If the mixture is u.sed for rockets the tallow 

 is omitted. 



ACuKiousi.v Considerate Invention has been 

 produced by a Krenchman, in the shape of a noise- 

 less clock, for use more especially in sick rooms. In 

 pl.tce of the usual pendulum, the hands are set in 

 motion by the unrolling of a chain, the end of which 



s fastened to a buoy floating in a tank of liquid. 

 This fluid escapes at a uniform rate, and can be util- 

 ized to feed a lamp wick, thus giving the apparatus 

 the double character of clock and lamp. When the 

 lamp is lighted the necessary diminution of liquid 

 takes place by combustion, and at other times by 

 carcfullj-rcgulated dropping. 



To Preserve Sheet-iron Smoke-stacks. — • 

 According to a correspondent of the Ariisan, a sim- 

 ple plan of preventing sheet-iron stacks from rusting 

 is as follows : If, before raising the new chimney, 

 each section, as it comes from the shop, be coated 

 with common coal-tar, then filled with light shav- 

 ings and fired, it will resist rust for an indefinite 

 period, rendering future painting unnecessary. In 

 proof of this, he cites a chimmey which was erected 

 in 1866, treated as above described, and is today as 

 bright as it was the d.ay it was raised, without hav- 

 ing a particle of paint applied since. The theory 

 by which he accounts for this result is that the 

 coal-tar is literally burned into the iron, closing the 

 pores, and rendering it rust-proof 



Mineral India Rubber. — An article formerly 

 considered worthless has been added to the useful 

 products, and is known as mineral India-rubber 

 asphalt. It is produced during the progress of 

 refining tar by sulphuric acid, and forms a black 

 material very much like ordinary asphalt, and elastic 

 like India rubber. When heated .so that the slimy 

 matter is reduced to about 60 per cent, of its former 

 size, a substance is produced hard like ebony. It 

 can be dissolved in naphtha, and is an excellent 

 non-conductor of electricity, and therefore valuable 

 for covering telegraph wires and other purposes 

 where a non-conducting substance is needed. Dis- 

 solved, the mineral India rubber produces a water- 

 proof varnish. The manufacture of the material is 

 said by an exchange to be profitable. 



OvertirfJing a Chimnev. — The simple and suc- 

 cessful method by which a high chimney was 

 recently overthrown is described by an exchange. 

 The stack was one hundred feet high by ten feet 

 square, and was on the Griswold Mills property, 

 New Bedford, Mass. It was undermined by knock- 

 ing out the bricks on the west and north sides, and 

 shored up by planks placed in the apertures. These 

 planks were liberally covered with tar and kerosene. 

 When the time arrived for felling the chimney, they 

 were fired. As tliey became sufficiently burned to 

 cease to support the chimney, the mass settled out 

 of the perpendicular to the north, and then cracked 

 and fell witli a crash to the ground. The bricks at 

 the top were scattered over quite an area, while the 

 iron coping was broken in quite a number of pieces. 

 Along the length of the chimney, to the height of 

 sixty or seventy feet, masses of brick for a length of 

 two feet or more clung together, and did not break up. 



A New y\NTi-FRiCTioN Metal. — The iridium 

 anti-friction metal is now being introduced into 

 England. This metal has undergone some very 

 successful tests in America, Professor Thurston 

 having compared the behaj ior of a brass made of 

 this alloy with one of the Pennsylvania Railro.ad 

 Company's standard phosphor-bronze bearings. 

 The tests extended over eight hours, the mean 

 speed of revolutions being 4(x) per minute. The 

 pressure at starting on each brass was 200 pounds, 

 which was increased by an additional 200 pounds at 

 the end of every two hours. The behavior of the 

 two alloys was, it is stated, practically identical. 

 The iridium metal contains no iridium, the term 

 apparently being used simply to indicate that the 

 material is a hard alloy, though it has a low melt- 

 ing-point, and can be cast round journals in place 

 in the same w.Ty as hahbitt-mctal. If desired, how- 

 ever, it can be cast and machined in the same way 

 as ordinary gun-metal. 



j^oiiie, Barni, aijd Gartleu. 



THE TOILET TABLE. 



We owe, in many cases, directly to 

 chemical science the various preparations 

 and devices by which the neatness and attrac- 

 tiveness of the person are secured, and such a 

 simple operation as washing the hands is 

 dependent upon complex chemical reactions, 

 which even at present are not well under- 

 stood. Soaj) is a combination of various 

 fattv acids with an alkali, such as soda or 

 potash, and is a true chemical salt. When 

 dissolved in water and applied to the skin, it 

 has the property of 'miting with the greasy 

 matters secreted by it, and removing them 

 along with other foreign matter. The action 

 is similar to that of the alkali itself, but is 

 greatly weakened and modified bv the fattv 

 acids with which the alkali is combined in the 

 soap. A double decomposition seems to take 

 place between the soap and the matters on 

 the skin, forming new and soluble compounds. 



There is no chemical principle involved in 

 the brushing of the hair ; but we may men- 

 tion the curious formation of electric sparks, 

 when dry hair is brushed or combed in cool, 

 dry weather. If this is done in a dark room, 

 quite good sized sparks may be seen playing 

 around one's head ; and this phenomenon 

 may be the origin of the legends of ancient 

 heroes, and the divine fires which blazed 

 about them in their infancy without burning 

 them. Similar sparks may sometimes be 

 seen in winter, wlien woolen, or, more espec- 

 ially, silk, underclothing is removed. In all 

 these cases, the electricity is simply produced 

 by friction, and is not formed in the body by 

 any of the vital processes. "Electric" hair- 

 brushes or combs may be mentioned only to 

 warn our readers against their use, as they 

 are entirely worthless. They not onlv pro- 

 duce no electricity whatever, but if the}- did, 

 it would not iiave the slightest effect upon the 

 hair. The same is true in regard to the so- 

 called electric tooth-brushes, hair-curlers, 

 corsets, and all the rest of the list. 



The use of fatty matters as a dressing for 

 the hair dates from a remote antiquity, but it 

 is a custom better honored in the breach than 

 in the observance. Their use is uncleanl}- in 

 the highest degree, and they serve no good 

 purpose whatever. Hear's grease has long 

 had a great reputation as a dressing for the 

 hair, but it does not difier from any other 

 coarse animal fat, and possesses no particular 

 beneficial pioperties. If a dressing of this 

 sort must be used, a solution of castor-oil in 

 cologne water is perhaps tiie best, or va.scline j 

 is a most excellent unguent which never turns 

 rancid ; but the occasions arc very few where 

 it is a necessity. 



Hair dyes are of two classes: those con- 

 taining lead, and those containing siher. 

 Neither are fit to u.sc, and serious illnesses ha\e 



