The paper describes results of measurementof reflected sounds in model buildings with aphoto-electric cell. By this method, it is possibleto obtain quantitative measurements of reflectionsin models with such materials of the same reflection coefficients as in actual cases.

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This is the report of the life test of the highgrade heating wires at the temperature of 1200°C. The method of the test is the same withwhich was used in the test of the low gradeheating wires. (Journal of the IlluminatingEngineering Society. Vol.XII. No.7.)
From this test it is concluded that;
(1) the life of the heating wire made in ourcountry has the longer life than that of theimported wire;
(2) the low grade wire TC made in our countryis not inferior to the imported high gradewire;
(3) it is important to determine how much theamount of the iron content effects on the lifeof a wire, and this problem will be solvedfrom the result of the chemical analysis;
(4) the sudden decrease of the current at thebegining of repeated heating and the uniformdecrease following it depend upon the oxidation of the wire.

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Cost of light obtained from an incandescenttungsten filament lamp, consists of the renewalcost of the lamp and the energy cost consumedby the lamp. The former decreases by using along burning lamp or a low efficiency lamp, while the latter to the contrary. The economicallife can be determined by knowing the lifeefficiencycharacteristic together with the ratioof the renewal cost to the energy cost perK.W.H. and it is shown that the economicallife depends simply on the ratio of the renewalcost to the electrical energy cost per K.W.H. inthe same sence and on the size of the lamp in the inverse sense.

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The present paper is the First Report of theCommittee on Vocabulary, Definitions and Symbols and describes the Japancse translation ofthe definitions of photometric quantities officially adopted at the 1921 and 1924 meetings of the Inteanational Commission on Illumination.

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