I50 



SCIENTIFIC NEV/S. 



[Sept. 1st, I? 



after having heated the carriage. It is said that the ordi- 

 nary size of gas flame is sufficient to heat a compartment. 

 To prevent the water being frozen when the carriage is not 

 in use, a little glycerine is mixed with it. We learn that 

 the system has been tried during the past winter on the 

 trains of the Glasgow and South Western Railway in Scot- 

 land, with very satisfactory results. 



Solubility of Carbonate of Lime. — In his lecture at 

 the Society of Arts, Mr. Dent points out that the solubihty 

 of carbonate of lime in water charged with carbonic acid not 

 only gives rise to very remarkable and curious incrustations, 

 but exerts a very considerable influence upon geological 

 limestone formations, the insoluble carbonate of lime being 

 deposited as a sedimentary rock. The white concretionary 

 limestone known as travertin, of which both ancient and 

 modern Rome are largely built, is an example of such a 

 deposit, which is taking place in some parts of Tuscany at 

 the rate of 6 inches a year. Carbonate of lime being deposited 

 from its solution in carbonic acid, serves to bind together 

 other materials with which it comes in contact in the course 

 of the deposition. It thus serves as the binding material 

 of several varieties of building stone, and becomes an im- 

 portant agent in the formation of rocks. 



The Builders of the Pyramids. — A personal inspection 

 of the pyramids of Egypt made by a quarry owner, 

 who spent some time recently on the Nile, has led 

 hini to the conclusion that the old Egyptians were better 

 builders than those of the present day. He states that there 

 are blocks of stone in the pyramids which weigh three or 

 four times as much as the obelisk on the Embankment. He 

 saw a stone whose estimated weight was 880 tons. But 

 then the builders of the pyramids counted human labour 

 lightly, and they had great numbers of subjects upon whom 

 to draw, and most of the work was done by sheer manual 

 labour and force. There are stones in the pyramids thirty 

 feet in length which fit so closely together that a penknife 

 may be run over the surface without discovering the break 

 between them. There is no machinery so perfect as to 

 make two surfaces thirty feet in length meet together in 

 unison as these stones in the pyramids do. It is supposed 

 that they were rubbed backwards and forwards upon each 

 other until the surfaces were assimilated to each other. — 

 Iron. 



Multiple Writing by Electricity. — Some few years 

 ago, at a time when there was a rage for all kinds of appara- 

 tus for multiplying fac-simile copies of handwriting, it will be 

 remembered that Edison brought out an ingenious " electric 

 pen," in which a small needle darting to and fro at great 

 speed made minute perforations in the paper, the printing 

 being effected by an inked roller, which was run over the 

 perforated paper like a stencil plate. The movement of the 

 needle was produced by means of a tiny magneto-motor 

 mounted upon the style, and driven by a couple of bichro- 

 mate cells. The cells had, however, to be of large size, the 

 motor requiring a good deal of current. Moreover, it was 

 impossible to write very fast with the pen in the first in- 

 stance, owing to its weight and the necessity for holding it 

 in a vertical position. Recently, M. Garel has succeeded in 

 obtaining similar results by more simple means. He writes 

 with an ordinary black-lead pencil upon very thin paper, 

 which is laid upon a smooth carbon block. The lead of the 

 pencil is connected to one terminal of a small induction coil, 

 and the carbon block to the other terminal. A spark then 

 follows the pencil point, and the paper can be used as a 

 stencil. — English Mechanic. 



Photo-Sculpture.^ We learn from the Photographic 

 News that there is now a tendency to revive the so-called 



photo-sculpture. The photographic guides introduced for 

 this process were ordinarily twenty-four in number, and all 

 the exposures were made simultaneously upon a sitter who 

 was seated with a circular battery of twenty-four cameras 

 directed upon him. Each of the resulting photographs 

 corresponded in its outline to the vertical section of the re- 

 quired bust in one position, and by trimming the photo- 

 graphs so as to obtain cardboard silhouettes, and using each 

 in succession as a guide in cutting out the clay, a rough 

 model of the sitter could be obtained. Photo-sculpture, 

 however, was not a success, and the difficulty of serving 

 twenty-four cameras with wet plates was very great. Now 

 the case is different, as with twenty-four cameras charged 

 with reliable dry plates, and all cameras brought into simul- 

 taneous action by an electric or pneumatic uncovering of the 

 lens, one may be reasonably sure of securing all the out- 

 lines with certainty. Renewed attention will probably be 

 given to photo-sculpture, and it has recently been the sub- 

 ject of discussion at the meetings of the Photographic 

 Society of France. 



The Telautograph. — As its name implies, this instru- 

 ment reproduces an autographic message. It is the inven- 

 tion of Mr. Elisha Gray, a well-known electrician, and it is 

 said that so far the experiments made with it have been 

 very satisfactory. The electric current is an important 

 factor in the invention, but the chief feature is the plate or 

 instrument on which the writing is done. No particular 

 kind of pen or pencil is required, in fact, a sharp-pointed 

 instrument of any kind will answer the purpose. The 

 paper on which the writing is done, and on which the auto- 

 graph is reproduced does not have to be prepared ; it is the 

 pressure on the plate which gives the impulse to the 

 machine, while the reproduction is brought about by a 

 tracing point, which may be a properly-linked pen, or even 

 an ordinary lead pencil, attached to a movable arm in the 

 receiving machine at the other end of the line. We learn 

 that a number of experiments with the machine have been 

 made at Highland Park, where Mr. Gray's laboratory is, 

 and that all of them have been of the most satisfactory 

 character. The circuit was not a very long one, but the 

 tests showed that the length of the circuit did not matter 

 much, and that the work could be done over many miles 

 of wire. 



Cork and its Uses. — Under this heading Industries con- 

 tains an interesting article, and from this we extract the 

 following : — Cork, on examination, is found to consist of 

 lifeless and empty cells, their walls being composed of a 

 substance differing from ordinary cellulose in many ways. 

 Thus it is practically impermeable to fluids, even under a 

 pressure of several atmospheres, yet quite pervious to gases, 

 as the simple experiment of submerging a cork under water 

 and exhausting the air readily shows. The cork, then, is 

 built of a multitude of minute water-tight air chambers, and 

 so long as the contained air does not escape we have a sub- 

 stance which reacts against pressure with the almost perfect 

 permanent elasticity of a confined gas, rather than with the 

 inferior elasticity of ordinary solids. The cork of an old 

 wine bottle shows admirably how long its elasticity is re- 

 tained, and experiments show that cork may be compressed 

 and released in water many thousand times without diminu- 

 tion of this valuable property. Hence arise some ingenious 

 recent applications ; thus gun-carriages are now being made 

 with cork instead of hydraulic " compressors," for storing a 

 portion of the energy of recoil of the cannon in order to run 

 it out again afterwards. In the same way a considerable 

 improvement in the working and efficiency of hydraulic 

 rams is obtained by using cork instead of air as a spring, so 

 as to insure regularity. 



