Letters Sent to Dr. Herman Schlundt, December 6, 1929

December 6th,1929. Dr. Herman Schlundt, Missouri University, Columbia, Mo. Dear Dr. Schlundt: Items Nos. 1 to 5 inclusive on Leads & Northrup's quotation G-8757, dated November 25th,1929, are necessary for assembling the type of equipment which we have for measuring the luminosity of radio-activo sinc sulphido. In addition to this equipment you need a special reference standard, which is quoted under item #6. We have had these reference standards made in Newark by an Engineering concern, and the cost has been around $25.00, with a slight additional charge for wrenches for us in fixing the position of the standard lamp. The reference standards which we have had prepared dave proven very satisfactory, although I presume they are not quite as nicely finished a job as Leeds & Northrup would prepare. In case you would care to have us obtain these reference standards, I would be glad to attend to the matter for you. In this connection I would suggest that you have two reference standards, otherwise you would never know whether it was the reference standard which was off or the photometer proper. I do not recall what the cost involved is for calibration of this apparatus, but it does not amount to a great deal. When you place the order for the equip- ment you should instruct them to ship same to the Electrical Testing Leboratories, East End Ave. and 80th St., N.Y.C. for calibration. At the time Leeds & Northrup advise you that shipment has been made you ahould take up with the Testing Laboratories the matter of calibration, and refer then to us for instructions as to exactly what you wish to have dons. It would be best to count on a months tâme. for the matter of calibration at the Testing Laboratories, for as a rule they are very buzy and there is usually some delay involved in getting to this type of work, inaszuch es it is special in nature. Sincerely yours, Vice President. HHBarker :RH