1867.] On an Apparatus illustrating the Voltaic Theory. 67 



The gradual diminution in the thickness of tlie coat of the stomach 

 is occasioned by the fibres of one layer or stratum radiating and be- 

 coming more and more delicate, while those of another and opposite 

 layer converge and become stronger and stronger ; it usually happening 

 that the stronger fibres supplement the weaker ones, so that the parietes, 

 although not of uniform thickness, are not suddenly strong and weak in 

 parts, but graduated. The only sudden thickening occurs in the shape 

 of two ridges which run along the lesser curvature about an inch apart. 

 The ridges in question are very distinct in the stomach of the Cat. 

 They can also be detected in a modified form in the stomach of the 

 Monkey a ad of Man. 



The dissections on which the above communication is based are pre- 

 served in the Museum of the Eoyal College of Surgeons of England ; 

 and the paper is illustrated by numerous original figures showing the 

 distribution of the fibres in the stomachs of the Herbivora, Carnivora; 

 and Omnivora. 



XVI. On a Self-acting Apparatus for multiplying and maintain- 

 ing Electric Charges^ with applications to- illustrate the Voltaic 

 Theory.^^ By Sir W. Thomson, E.R.S., Glasgow University. 

 Received June 19, 1867. 



In explaining the water-dropping collector for atmospheric electricity, 

 in a lecture in the Royal Institution in 1860, I pointed out how, by 

 disinsulating the water-jar and collecting the drops in an insulated 

 vessel, a self-acting electric condenser is obtained. If, owing to elec- 

 trified bodies in the neighbourhood, the potential in the air round the 

 place where the stream breaks into drops is positive, the drops fall 

 away negatively electrified ; or vice versa, if the air potential is negative, 

 the drops fall away positively electrified. The stream of water descend- 

 ing does not in any way detract from the charges of the electrified 

 bodies to which its electric action is due, provided always these bodies 

 are kept properly insulated; but by the dynamical energy of fluid- 

 motion, and work performed by gravity upon the descending drops, 

 electricity may be unceasingly produced on the same principle as by 

 the electrophorus. But, as in the electrophorus, there was no provision 

 except good insulation for maintaining the charge of the electrified 

 body or bodies from which the induction originates. This want is 

 supplied by the following reciprocal arrangement, in which the body 

 charged by the drops of water is made the inductor for another stream, 

 the drops from which in their turn keep up the charge of the inductor 

 of the first. 



To stems connected with the inside coatings of two Leyden phials 

 are connected metal pieces, which, to avoid circumlocution, I shall call 

 inductors and receivers. Each stem bears an inductor and a receiver 



