242 Prof. E. WaYtm&nn' sjburth Memoir on Induction. 



to the cases of induced currents. Dr. NeefFof Frankfort on 

 the Maine, in 1835*, and M. Masson in the following yearf, 

 have made very conclusive experiments on this subject. An 

 instrument described by M. Poggendorff under the name of 

 inversorX, is intended to render the current of an ordinary 

 battery at the same time discontinuous and in an alternate 

 direction through a given conductor. 



117. At the present day the employment of induced cur- 

 rents seems to become more and more general. In place of 

 the original magnets employed in the apparatus of Ritchie§, 

 Pohl||, Pixii^, Saxton**, Clarkeftj StorerJ:}:, and others, a 

 simple voltaic pair has been substituted, and an instrument has 

 been constructed, of small size, easy of transport, and producing 

 almost unlimited effects, called an electro-electric machine, or a 

 shock-machine. M. Bonijol constructs this machine with such 

 perfection that it has been generally adopted, and there is at 

 the present day scarcely an hospital where it is not found. It is 

 employed in the treatment of a multitude of nervous affections; 

 in that of amaurosis§§, in assisting parturition ||||, and as a dia- 

 gnostic to ascertain the state of vitality of the foetus. 



118. I have had more than one opportunity of convincing 

 myself that many persons make use of the shock-machine 

 without understanding either its construction or its theory. 

 This maciiine, arranged on a different plan, might be rendered 

 both more intelligible in its mode of action and more useful to 

 the physicist and the physiologist. I will point out some of 

 the cases in which it may be employed, and afterwards the 

 arrangement applicable to each of them. 



119. A voltaic current being given, it may be proposed — 

 1. To render it discontinuous, without changing its direc- 

 tion, in a conductor a ; 



* Das BUtzrad, ein Apparat zu rasch abwechselnden gnhanischcn ScklieS' 

 sungen und Trennungen. Pogg. Ann., vol. xxxvi. p. 352, and vol. xlvi. 

 p. 104. 



f Comptes Rendus de PAcad. des Sciences de Paris, vol. iv. p. 456. 



X Pogg. Ann., vol. xlv. p. 372 and 385. § Phil. Trans., Oct. 1833, 



II Pogg. A/m., vol. xxxiv. p. 185 and 500. 



H Ann. de Ch. et de Phi/s., vol. 1. p. 322. 



** Phil. Mag. N. S. vol. ix. p. 360. ft Ibid. p. 262. 



XX Pogg. Ann , vol. Ixi. p. 417, 1844. 



§§ Cunier, Dr., Annates d' Oculistique, vol. xii. and vol. xvi., where will 

 be found a memoir by Dr. Hcering On the Employment of the Electro-mag- 

 netic rotatory apparatus in Diseases of the Eyes. 



nil See on this subject, P. Kerz, De ctcctro-viagvetisvii vi et iisu in arte 

 obstetricia. Bonn, 1846. — J. A. Schmidtmuller, Ilandbuch der medizinischen 

 GcburtsJiulfe. — T. Radford, Galvanism applied to the treatment of uterine 

 Haemorrhage. Manchester. — Von Kilian, Die Geburtslchre von Seiten der 

 Wissenschaft und Kunst, — Neue zeitschrift fiir Gcbtirtsfcunde, von H. Bursh, 

 d'Oiitrepont, &c., vol. xvi. No. 26, &c. 



