File:Practical radiography - a handbook for physicians, surgeons, and other users of X-rays (1901) (14777626933).jpg

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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o avoid any oil getting between the ebonitediscs. Many of these precautions, however, may be dispensedwith, or, at least, considerably lessened, if the machine isenclosed in a dust-proof glass case, from which only theterminals are projecting. As a matter of fact, several ofsuch machines, which, by the courtesy of Mr. J. Wims-hurst, we were able to inspect, and which had not beenused for considerable periods, at once excited without anyprevious attention (Fig. 14). The spark length which a machine should give whenproperly worked ought roughly to equal the radius of therevolving plates. Much, however, depends upon the posi- 42 Practical Radiography tion of the brush neutralizes. The latter must be so bentthat the brushes touch the discs during the whole periodof rotation ; keeping one neutralizer in a nearly verticalposition, the other should be turned so far that the sparkbetween the dischargers attains a maximum when graduallydrawn out. This is generally the case when the neutralizes
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Fig. 14. are at right angles to each other and equidistant from thecollectors. It is of course important to determine the polarity of thedischarging knobs in order to properly connect the tube ;the positive electrode may be identified by the sharp,hissing noise it emits when in the horizontal position. The advantages of statical machines for X-ray workmay be stated as follows :— (1) Simplicity.—Dispensing entirely with batteries,accumulators or current from the mains, the statical Sources of Electric Energy 43 machine may be said to be essentially mobile and to makethe operator independent of local circumstances and diffi-culties. The further absence of induction coils, measuringand controlling instruments and accessories both cheapensthe installation in first cost and also minimizes the riskof breakdowns inseparable from more complicated arrange-ments. (2) Maintenance.—Very little—if any—attention needbe given to the machine when not in use, and it is alwaysready—without

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