Excerpt from The Illuminating Engineer, Vol. 13: Jan. 1920 to Dec. 1920
The circumstances in which apparatus for measuring illumination are applied and the number of purposes they serve are now so varied that there is room for quite a number of different forms. In each case a decision has to be taken as to the relative importance of accuracy and convenience. The tendency now is towards the design of very simple and portable instruments, in some cases allowing a reading to be taken by mere inspection of the scale without moving a lever to obtain balance. Such types form a valuable supplement to the more precise and accurate forms. One might suggest a rough classification into illumination-photometers and illumination-gauges, the latter serving merely to enable a rough determination of the order of illumination to be obtained with extreme ease and being suited to particular problems. For example, instruments for use in accurately determining conditions of illumination in streets, factories, picture theatres, mines, etc., demand qualifications that can only be met by a very comprehensive form of apparatus capable of adjustment according to the problem dealt with.
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- PublisherForgotten Books
- Publication date2018
- ISBN 10 0656500344
- ISBN 13 9780656500345
- BindingHardcover
- Number of pages367