360 



SCIENCE. 



FIG. 4- 



Fig. 2. 



Faure battery is similar to the above : — Two sheets of 

 lead are taken, about 7X m - wide ; one about 23in. long 

 and about i-25th of an inch thick, the other i 5in. long 

 and 1-48 in. thick. Each of these is furnished with a 

 strong strip of lead at one of its ends. Each sheet has a 

 layer of red lead spread on its surface, the lead being 

 made into a paste with water, the larger sheet having 

 about 800 grammes on its surface, and the smaller 700 

 grammes. On each surface a sheet of parchment is laid, 

 and the whole is introduced into a sheathing of thick 

 felt. The sheets are laid one above the other ; at the 

 same time several bands of india-rubber are placed in an 

 oblique fashion, as shown in Fig. 3. The roll is placed 

 in a leaden jar strengthened by copper bands, and 

 covered in the interior with red lead and felt. The cell 

 then presents the appearance shown in Fig. 4. One of 

 the pieces of lead which jut out is curved and soldered 

 to the outer jar, acidulated water is put in, and the bat- 

 tery is ready for work. 



We give the above figures as a guide, but there is no 

 special reason for adhering to them, and it may be 

 doubted whether either the parchment or felt is an abso- 

 lute necessity ; for good batteries have been constructed 

 by painting stout lead-foil with red lead made into paste 

 with water slightly acidified with oil of vitriol, and wrap- 

 ping the plates in flannel or canvas which has been pre- 

 viously coated with the red lead paint. The painted 

 surfaces are of course put together. Thin lead is used 

 to keep the weight down as much as possible and to re- 

 duce the cost. 



THE LESSON OF THE COMET; DOES IT SHOW 

 A NEW FORCE? 

 By Samuel J. Wallace, Washington. D. C. 



There is one important consideration in relation to a 

 comet and its tail which does not seem to have been pro- 

 perly noticed. A comet is generally supposed to be a 

 mass, cloud or assembly of masses, particles and possi- 

 bly gases, which travel together through the heavens, but 

 do not actually form a single cohering body. 



Now the remarkable point is this. When this assem- 

 bly of matter of various sizes and conditions approaches 

 the sun at a great velocity it seems to be acted upon by 

 two forces in opposite directions at the same time, the 

 one driving it forward toward the sun and the other driv- 

 ing it out away from the sun, and apart laterally. 



And these two forces seem to act at different rates on 

 different parts of the matter, so as to drive some parts 

 torward, forming the head of the comet ; to drive oilier 

 parts forward with a less force, and spread them apart, 

 forming the brighter part of the tail ; while they act to 

 actually drive other parts away into space, as the brush 

 of the tail. 



This is an action like that familiar to us in concentrat- 

 ing ores and in separating grain from the chaff. When 

 ores are powdered fine and sifted down a shaft, up which 

 a strong current of a ; r is blown, the heaviest and richest 

 particles fall through the opposing current to the bottom 

 while the lighter and worthless particles are blown up and 

 away. In this manner the rich ore is separated from the 

 poor, and in a like way grain is separated from the chaff. 

 This occurs because there are two forces acting against 

 each other — the wind and gravitation — which act at dif- 

 ferent rates on the different particles and separate them. 



The comet looks as if it was undergoing this very op- 

 eration of concentration, or separation of the heavy parts 

 from the light parts, under the action of gravity driving 

 inward to the sun or some other opposing force driving 

 outward and apart. 



What makes this so remarkable is that the substance 

 of the planets seems to have been separated in this very 

 same manner. If we take the recognized specific gravi- 

 ties of the several planets and set them down in the order 

 of their occurrence from Neptune, the furthest, inward to 

 Mercury, the nearest the sun, beginning with one as the 

 unit, we will find a gradual increase in weight per cubic 

 foot from one for Neptune up to about nine for Mercury. 

 If we set down the velocity of the planets in the same 

 manner we will find the singular fact of an increase in the 

 same way, from one for Neptune to about nine for Mer- 

 cury. So that the velocity and the weight per foot increase 

 together in a way that looks very suspicious of some con- 

 nection between them. 



What makes it look so singular is that the distance from 

 the sun decreases almost in the verv ratio of these two 

 proportions multiplied into each other; or in the very 

 way which it would do if the planets were formed of 

 matter which had been concentrated by the heavy parts 

 being driven toward the sun by gravity and the lighter 

 parts being driven away by some other force — such as 

 that which seems to be driving off the tail of the comet— 

 so that each planet was formed of matter separated by 

 its specific gravity in a general way, according to its dis- 

 tance from the sun and its velocity. Another thing which 

 confirms this singularity is that the average weight of the 

 meteoric masses which fall on to the earth, made up mostly 

 of iron and some lighter rock, is very nearly that of the 

 earth itself, taken as a whole, or about five and a half on 

 the same scale, due to its position and velocity. 



All this leads us to suppose that there is a force driv- 

 ing outward from the sun, as gravity drives toward it, but 

 acting in proportion to the size of particles as gravity acts 

 in proportion to their weight, which separates matter so 

 that its average distance from the sun and its velocity 

 shall conform to its average weight. 



If this is true, as it seems, it throws light upon an ob- 

 scure point, which may be considered as one of the most 

 sublime within the reach of science ; the nature of that 

 wonderful mystery of gravitation itself, which holds and 

 moves all the innumerable hosts of heaven in their ever- 

 lasting circuits. 



The course of modern thought is to render inconceiv- 

 able the action of gravity as of an immaterial agent. 



The theory of Lesage that it is the result of converg- 

 ing corpuscles of wave beats from all sides tending to 

 drive bodies together is both sublime and in accordance 

 with the habits of modern thought. But it utterly fails 

 in one half of the problem. It does not explain what be- 

 comes of the dynamic energy of this force after it strikes 

 a mass of matter, by which disappearance it is supposed 

 to produce a shadow outward on all sides, to which the 

 result of gravitation of masses to each other is attributed. 



But if it should appear that there is a force thus going 

 outward from the sun and other matter, as comets and 

 planets in this way seem to indicate, then we are compelled 

 to account for it also, which is the very force that 

 Lesage's theory failed to show, and which his force re- 

 quires for its complement. 



