801 SEC. 18. BIOLOGY. 



3793g. Moistened Battery, with constant Action. 



M. Trouve, 6, Rue Therese, 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," &c., &c., &c. 



VIII. APPARATUS FOR INVESTIGATING THE FUNC- 

 TIONS OF MUSCLES AND NERVES. 



3794. Muscle Telegraph. T. Hawksley. 



3795. Apparatus for investigating the action of Poisons 

 on Muscles. T. Lander Brunton. 



3796. Double Lever Apparatus for demonstrating the 

 movements of the auricles and ventricles. T. Lander Brunton. 



3797. Apparatus for demonstrating the influence of Heat 

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



T. Lander Brunton. 



3798. Rosenthal's Rotating Myographion, constructed by 

 Th. Welmann, of Munich. Prof. Rosenthal, Erlangen. 



This myographion, lately constructed by the exhibitor, and not hitherto 

 described, consists of a large glass plate, which is swiftly rotated by a weight 

 round a horizontal axis. As soon as the desired velocity is attained, the glass 

 plate is slightly displaced parallel to itself in the direction of its axis. It makes 

 exactly one revolution in its new position, and then returns of itself to its 

 original position in order to keep on rotating. Whilst this one revolution is 

 taking place the excitation and contraction curves are marked by a very 

 simple mechanism. The time of duration can be esftctly determined by a 

 simultaneous tracing of a tuning fork curve. Eor investigations on reflex 

 action, especially for measuring the time of the (so called by the exhibitor) 

 " quertietung" (cross conduction), a contrivance is made by means of which 

 two muscle curves can be simultaneously traced. 



In order to determine very exactly the point at which the contraction curve 

 commences, the movement of the left of the muscle is very considerably 

 magnified. As the form of the muscle curve given by this apparatus cannot 

 be depended on, it will not serve for studying its actual details. 



The time of revolution of the glass plate may vary from two to half a 

 second. It was impossible to measure with any apparatus hitherto constructed 

 a space of time of such length with sufficient rapidity. 



The linear velocity of the instrument revolving at its quickest rate amounts 

 to about 2,500 mm. in a second; values of O'OOl second can thus be easily 

 measured. 



