952 SEC. 18. BIOLOGY. 



3793g. Moistened Battery, with constant Action. 



M. Trouve, 6, Rue Theresc, Paris. 



This battery is composed thus : Between two discs, one made of copper 

 the other of zinc, forming the two electrodes, are piled rounds of blotting 

 paper. The lower half of these rounds is previously saturated with sulphate 

 of copper, the other half with sulphate of zinc. It is continuously uni- 

 form, and lasts a long time. It is applied with great efficacy to electric 

 clockwork, to telegraphy in general, and to all electrical apparatus having 

 a resisting circumference. Moreover it forms part of several apparatus 

 exhibited by the same inventor, particularly of the " military telegraph," the 

 "apparatus with continuous current," &e., &c., &c. 



VIII. APPARATUS FOR INVESTIGATING THE FUNC- 

 TIONS OF MUSCLES AND NERVES. 



3794. Muscle Telegraph. T. Ilawksley. 



3795. Apparatus for investigating, the action of Poisons 

 on Muscles. T. Laudcr Brunton, F.R.S. 



3796. Double Lever Apparatus for demonstrating the 

 movements of the auricles and ventricles. 



T. Lander Brunton, F.R.S. 



3797. Apparatus for demonstrating the influence of Heat 

 and Cold and the action of Poisons on the Prog's Heart. 



T. Lander Brunton, F.R.S. 



The fact that heat accelerates and cold retards the pulsations of the heart is 

 one of such fundamental importance, both in regard to a right understanding 

 of the quick pulse, which is one of the most prominent symptoms of fever, 

 and to a correct knowledge of the proper treatment to apply when the heart's 

 action is failing, that for the last year or two the exhibitor has been accus- 

 tomed to demonstrate it as a lecture experiment. The apparatus used is 

 exceedingly simple, but it answers its purpose well, and by its means the 

 pulsations of the frog's heart can be readily shown to several hundred persons 

 at once. It was exhibited at the meeting of the British Medical Association 

 in London more than two years ago, and a description of it appeared in the 

 " British Medical Journal ? ' for August 23, 1873; but as there is reason to 

 believe that few physiologists have seen either the instrument or its descrip- 

 tion, it may not be amiss to add a few words regarding it here. It consists 

 of a piece of tin plate or glass three or four inches long and two or three 

 inches wide, at one end of which an ordinary cork, cut square, is fastened 

 with sealing-wax in such a manner that it projects half an inch or more 

 beyond the edge of the plate. This serves as a support to a little wooden 

 lever about three inches long, a quarter of an inch broad, and one-eighth of 

 an inch thick. A pin is passed through a hole in the centre of this lever, and 

 runs into the cork, so that the lever swings freely upon it as on a pivot. 

 The easiest way of making a hole of the proper size is simply to heat the pin 

 red hot, and then to burn a hole in the lever with it. To prevent the lever 

 from sliding along the pin, a minute piece of cardboard is put at each side of 

 it, and oiled to prevent friction. A long fine bonnet straw or section of one 



