Directions for class work in practical physiology, elementary physiology of muscle and nerve and of the vascular and nervous systems / by E.A. Schäfer.

  • Edward Albert Sharpey-Schäfer
Date:
1901
Catalogue details

Licence: In copyright

Credit: Directions for class work in practical physiology, elementary physiology of muscle and nerve and of the vascular and nervous systems / by E.A. Schäfer. Source: Wellcome Collection.

    25/148 page 11
    completed through a wire attached to a rider (r) which slides along the rheochord wire. When r is in contact with b the whole difference of potential between a and b—this difference de- pending upon the e.m.f. of the battery and the resistance of the rheochord wire—is operative in producing a current through the experimental cir- cuit. When r is at the middle of the rheochord wire only one-half of this difference of potential conies into play, and so in proportion to the dis- tance between a and r as compared with the whole length of the wire. Thus if the wire be ioo centi- metres long and r be placed at one centimetre from a only y-i-y of the total difference of potential will be operative and a proportional current will be diverted into the experimental circuit. When this form of rheochord is to be used, the resistance of the experimental circuit must always be very great: this is invariably the case in physiological experiments. In another form of rheochord (Poggendorff’s) the wire is doubled on itself, and a rider (r) bridges across and forms a short circuit between the two
    No text description is available for this image
    No text description is available for this image
    No text description is available for this image