File:Practical radiography - a handbook for physicians, surgeons, and other users of X-rays (1901) (14571091749).jpg

English: Hand showing Arteries Injected with Mercury.(By the Medical Supply Association, 12 Teviot Place, Edinburgh.) From: PRACTICAL RADIOGRAPHY A HANDBOOK FOR PHYSICIANS, SURGEONS,AND OTHER USERS OF X-RAYS by A. W. Isenthal and H. Snowden Ward

Identifier: practicalradiogr00isen (find matches)
Title: Practical radiography : a handbook for physicians, surgeons, and other users of X-rays
Year: 1901 (1900s)
Authors: Isenthal, A. W Ward, H. Snowden (Henry Snowden), 1865-1911
Subjects: Radiography X-rays X-rays Radiography X-Rays
Publisher: London : Published for The Photogram, Ltd. by Dawbarn and Ward, Ltd.
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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confidently say, is limited to thecharging of accumulators, as previously described; andalthough even for this purpose they are but seldom metwith, we will give a brief outline of their principle andconstruction for those whom it may interest. In 1821 Professor Seebeck of Berlin found that an elec-tric current was produced when heat was applied to one ofthe junctions of a circuit consisting of two different metalsin contact. The generation of current also takes place whenone of the junctions is cooled, or—generally speaking—whenever, and as long as, there exists a difference of tem-perature between the two junctions. The direction of theresulting current is always from the warmer to the colderjunction, and the strength of the current increases with thedifference in temperature. The E.M.F. of such a thermo-electric couple depends upon the nature of the metals incontact, and for practical purposes attains a maximum inthe case of the couple Bismuth-Antimony, amounting to Plate III.)
Text Appearing After Image:
Hand showing Arteries Injected with Mercury.(By the Medical Supply Association, 12 Teviot Place, Edinburgh.) Sources of Electric Energy 33 0000057 volts for each Centigrade degree difference oftemperature. In order, therefore, to produce any usefulE.M.F. within workable limits of temperature, we mustconnect several thermo-electric couples in series (similar togalvanic cells in series), that is, the antimony element ofeach couple to the bismuth element of the next couple.Such a combination constitutes a thermo-electric batteryor thermopile. In practice a very great number of couplesare joined together, and are so arranged that the heat,which in most instances is furnished by atmospheric gasburners, is directed to all the junctions of one kind, whilst

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