An international system of electro-therapeutics : for students, general practitioners, and specialists . the various surgical-instrument makers throughout most of our large cities. Those made bythe Waite & Bartlett Manufacturig Company are perhaps the most widelyknown.^ The Massey current-controller is a modification of the oneknown as the old Butler rheostat. The above-named firm have under-taken its modification, and to-day it looks as follows : The disc is madeof slate with the cone-shaped surface roughened for retaining the graphitecoating. The advantage of the slate is that it does not be
An international system of electro-therapeutics : for students, general practitioners, and specialists . the various surgical-instrument makers throughout most of our large cities. Those made bythe Waite & Bartlett Manufacturig Company are perhaps the most widelyknown.^ The Massey current-controller is a modification of the oneknown as the old Butler rheostat. The above-named firm have under-taken its modification, and to-day it looks as follows : The disc is madeof slate with the cone-shaped surface roughened for retaining the graphitecoating. The advantage of the slate is that it does not become soiledlike the martle, and it always presents a neat appearance. The brushfor moving over the resistance surface is made of spring-brass nickelplated, sufficiently broad to span the broadest part of the leadenportion, and the spring is split up in several places to insure perfectcontact over the entire surface upon which it rests. One of the binding-posts attached to the wooden frame surrounding the disc connects with. t:,: FlQ. 33. » Augustin H. Goelet, : The Electro-Therapeutics of Gynaecology, voL i, pp. 135,136,137. A-238 BLEYER. the base of the leaded surface by means of the spring contact underthe cap, and the other with the central pivot, to which the brush isattached by a lever; so that there is a break, so to speak, between thetwo when the brush stands at the point marked start, removed fromthe coated surface. As the brush is moved upon the graphite the resist-ance is diminished the nearer it approaches the base. The graphite,which is really a good conductor of the current when spread out over aflat surface like this, offers a considerable resistance. In order to in-crease the resistance at the start, so as to permit the current to be turnedon gradually from a battery of a great number of cells, it is necessary tomake the graphite coating ver}^ much thinner there than elsewhere, andif too much has been put on it should be rubbed off until its presence is
Size: 1136px × 2199px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectuterus, bookyear1894
