Identifier: practicalpointsi00judd (find matches)
Title: Practical points in the use of X-ray and high-frequency currents
Year: 1909 (1900s)
Authors: Judd, Aspinwall
Subjects: X-rays Electrotherapeutics Radiography X-Rays Radiography
Publisher: New York : Rebman Company
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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dbe replaced. The two ends of the windings inthe secondary are brought up through the jacketat opposite ends of the coil, and become the ter-minals. Attached to either one or both of theseterminals, is a sliding metallic rod or lever. Byapproaching or withdrawing these rods fromeach other, the length of the spark gap betweenthe terminals is controlled. The distance be-tween these rods should never be as great as thecapacity of the coil. That is—in a twelve-inchcoil, the poles should be placed six inches, eightinches or ten inches from each other, dependingupon the quantity of current that we desire atthe time. (See Fig. B, Rhumkorff coil.) 38 X-Ray and High-Frequency Currents Ammeter This is an instrument for measuring the quan-tity of current used in the primary circuit of theX-ray coil, and is a most important instrumentand should be a part of every X-ray equipment,as by means of it the operator can tell just how In the simplest form, ^ A A (\(\(\(\0(\(\f\ much current he is using
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Fig. B.—Figure of an Induction Coil.The description will be found in the text pages 36-37 it consists of a steel needle balanced on a point,the same as used in the ordinary compass.Underneath this is placed a coil of wire throughwhich the current passes. The stronger the cur-rent, the further the needle is deflected fromzero. As usually constructed for commercialpurposes, however, there is in addition a coilspring, wThich brings the needle back to zero assoon as the current is shut off. The Coil and Accessories 39 Multiple Spark Gaps These are made in two styles. One style con-sists simply of a row of brass balls, mounted onan insulating rod and separated about one-eighthof an inch from each other. A rod is arrangedto slide over the top of the balls, so that a sparkgap can be used of from one-eighth of an inchup to about two inches. The other type con-sists of a series of points placed about one-sixteenth of an inch away from a metal disc,usually an inch in diameter. Multiple sparkg

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