MECHANICAL IMPROVEMENTS AND INVENTIONS. 



Bflg 



of a kind of aneroid barometer, being a 

 metallic case with compressible sides, which re- 

 tain tin- impression of the strongest hydrostatic 

 piv.-suro imparted, to them. It descends in a 

 plumb-lino course, by means of a weight at- 

 t.id.i (1, which disengages itself the instant the 

 li<>n< .in is struck, and a float brings it to the 

 siirt'iic-e again. The registration is very exact, 

 being made through the instrumentality of a 

 hydraulic [ 



An instrument called the bathometer, which 

 records tine variations of gravitation, is re- 

 ported to indicate the varying depths of the 

 ocean, in the course of a vessel, with approxi- 

 mate correctness. Dr. Siemens, the well-known 

 English engineer, is the inventor. It consists of 

 a steel tube slightly distended at the extremi- 

 ties, with u movable bottom of thin, flexible 

 steel, and tilled with mercury. The outward 

 pressure of the column of mercury upon the 

 diaphragm is compensated for by a spring, 

 which is coiled about the tube. Any increase 

 of pressure on the outside of the tube causes 

 the spring to yield, and the disk at the bot- 

 tom to rise and lift the column of mercury. 

 A diminution of pressure, on the other hand, 

 allows the mercury by its weight to push the 

 spring outward and sink in the tube. The 

 mercury at the top of the tube rises into a 

 slight mound, or sinks into a hollow, in ex- 

 actly the same proportion as the disk is con- 

 tracted or expanded. 



The Pattinson process for extracting silver 

 from lead, when not more than three ounces 

 of silver is contained in a ton, by allowing the 

 lead to cool and crystallize in a large vessel, 

 and removing the crystals, has been improved 

 by the Messrs. Cookson, of Howdon, England. 

 The molten metal is agitated by an injected jet 

 of steam, while cold water, poured over the 

 surface, facilitates the crystallization. The 

 melted metal is made to run from one pan into 

 another so ns to save labor. The came method 

 can be used in refining hard lead. The cost is 

 only about one-sixth of that by the old method. 

 The wear and tear of the machinery, however, 

 are considerably greater. 



A couple of instruments, shown at a soiree 

 of the Royal Society by Mr. \V. F. Stanley, are 

 contrived to register exactly the average baro- 

 metric and thermometric changes. They nre 

 called the chrono-barometer and chrono-ther- 

 mometer, and consist of a combination of those 

 instruments with a clock. A clock-movement 

 is fitted with a mercurial barometer or ther- 

 mometer as a pendulum. The rising and sink- 

 ing of the mercury alter the centre of gravity, 

 and consequently the rapidity of the stroke. 

 The dial-plate is the same as in an ordinary 

 timepiece. The variations of time, therefore, 

 for a given period are in exact proportion to 

 the mean atmospheric or thermometric changes 

 in the same period. 



M. Charles Chamond, of Paris, has succeed- 

 ed in perfecting an invention made some seven 

 or eight years back for generating electricity 



by heat, so that it is now possible to produce 

 electricity cheaply and on a large scale. The 

 principal improvement made in the process it) 

 a met IK. 1 1 of casting the metallic thcrm<> 

 trie bars in hot moulds, thus preventing the 

 formation of microscopic fissures, which occur 

 in all materials cast in cold moulds, and a 

 method of fastening the metallic plate in the 

 part of the bar exposed to the beat. In the 

 old apparatus the plate became gradually oxi- 

 dized from contact with the bar of metal or 

 crystallized mineral, and thus became a resist- 

 ant to the passage of the electrical waves, and 

 the bars also became useless, after a while, 

 from the oxidation which penetrated the mi- 

 nute cracks. The bars are arranged in the 

 new machines usually in a circle. A certain 

 number of elements are superposed, forming a 

 cylinder, the interior of which is to be heated : 

 they are isolated by the interposition of mica 

 or amianthus. Within the pile is a tube of 

 fire-clay, with perforations at intervals. The 

 heating is by means of a Bunsen burner with 

 coal-gas for fuel ; but M. Chamond has per- 

 fected an arrangement by which coke may be 

 employed for fuel in cases when gas is not 

 available. The bars are also heated by the 

 radiation of the fire-clay tube which remains 

 at a red heat, and by contact with the flame aa 

 it rises. Each bar is provided with pole-plates, 

 which are fastened in different positions ac- 

 cording to whether it is desired to develop 

 a tension or a quantity current, and according 

 to the degree of tension or the quantity to be 

 produced. 



A magneto-electric machine, recently in- 

 vented by M. Alfred Niaudet Brguet, is con- 

 structed as follows: Twelve coils of wire, 

 similar to those used in the Gramme machine, 

 are inserted in the periphery of a wheel, re- 

 volving on an horizontal axis between the poles 

 of two fixed magnets. The coils are connected 

 together, and are thus analogous to the ele- 

 ments of a galvanic battery. According to 

 Lenz's law, each coil in half its revolution is 

 traversed by a direct current, and in its other 

 semi-revolution by an inverse current. Two 

 metallic springs placed in contact with copper 

 strips leading from each pair of coils act as 

 current-collectors. The apparatus may be com- 

 pared to two batteries of six elements united, 

 in which. the elements are connected together 

 for tension. This machine produces a per- 

 fectly continuous current. 



Experimenters in France and Germany have 

 been occupied of late with the notion of utiliz- 

 ing the heat of the sun as a motive force. M. 

 A. Mouchot constructed an apparatus at Tours 

 which, by ordinary spring weather, raised steam 

 of 80 pounds' pressure within three-quarters of 

 an hour, in a five-gallon boiler, in which the 

 water had an original temperature of 20 0. : 

 the temperature in 40 minutes was 121 C., and 

 afterward it rapidly rose to 168, and the steam 

 pressure to 75 pounds. At noon of the same day 

 a pressure of 75 pounds was reached in 15 min- 



