950 SEC. 18. BIOLOGY. 



3788a. Copy of " Ueber einen neuen Respirations Apparat." 



Dr. Max Pettenkofcr, Munich. 



3788b. IVlosso's Plethysmograph, modified by Kronecker. 

 and photograph of the same. Prof. Gerald Yeo. 



3788c. Kronecker's Improved Manometer for frog's 

 heart. Prof. Gerald Yeo. 



VIL ELECTRICAL APPARATUS USED IN PHYSIO- 

 LOGY. 



3789. Hermann's Universal Commutator, with adjustable 

 contact-springs. Prof. Dr. L. Hermann, Zurich. 



This apparatus may be turned by hand or by water power, and admits of 

 many physical and physiological applications, e.g. : 1. Closing a simple 

 electrical circuit (" interrupter "). 2. Change of direction in a simple 

 electrical current (" in versor "). 3. The same in two circuits, for instance, 

 in determining resistance in a polarisable conductor, by Wheatstone's 

 method, under currents of changing direction. 4. Choice between opening 

 or closing induction currents (Dove's " Disjunctor "). 5. Determination of 

 the polarisation residuum in a conductor after shutting the current (like 

 Siemens's " Commutator "). 6. Comparison of two residua of polarisation, 

 by connecting the two conductors with the galvanometer, one opposite to 

 the other. 7. Many physiological rheotomic inquiries. 



3790. Hermann's Non-Polarisable Electrodes, of large 

 form. Prof. Dr. L. Hermann, Zurich. 



By this apparatus a nerve may be connected with any number of non- 

 polarisable electrodes in a small space, for instance, in the wet chamber of a 

 myograph. The ends of the zinc wires, well amalgamated, receive a covering 

 of clay, mixed with saturated solution of sulphate of zinc, and above this a 

 small quantity of clay mixed with O 1 6 per cent, solution of chloride of sodium. 



3790a. Becquerel's Thermo-Electric Apparatus for 

 Physiological Purposes. M. Ruhmk&rff. 



3791. Electric Excitors. T. Hawkslcy. 



3792. Daniell's Constant Current Batteries for Clinical 

 use. T. Hawksley. 







3793. Dr. Herbert Tibbitt's Constant Current Batteries 

 and Induction Apparatus. T. Hawksley. 



3793h. Physiological Recording Apparatus, capable of 

 moving at any speed from three inches to six feet per minute. 



Dew. Smith. 



