
AVERAGING ONCE a year someone asks this department why telescope mirrors have to be so thick, and now comes an inquirer who reasons that if mirrors were thinner they would have just that much less weight to support and therefore wouldn't sag any more than thicker ones, also would adapt themselves to temperature changes more quickly.
This sent us to a remembered file of papers containing an article in the Journal of the Royal Astronomical Society of Canada, July-August 1935, in which Harold C. King, Calgary, Alberta, similarly contested the statement in "A.T.M.," page 75, that mirror disks could have thicknesses not less than "one eighth of their diameters, one sixth still better, and which was never rebutted. "Some dicta," he stated, "are grooved to be wrong by their supposed explanations. If there is anything illogical in the explanation there is probably something wrong with the whole proposition.
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