This letter was asking question on using telescope mirrors made of cast aluminium or other light metal, which could be cheap and easy to make and also what kind and size of grating, its makers and price to building a solar observatory.

This letter was to inform that C. V. Raman was greatly obliged for M. K. Vainu Bappu's letter of the 8th July 1954. He got one of the Bausch and Lomb catalogues and was very favourably impressed by it and intend to go ahead and purchase one or more of these gratings for his work.

The letter is from C. V. Ramam, Raman Research Institute to M. K. Vainu Bappu, Nizamiah Observatory asking about using telescope mirrors made of cast aluminium and about diffraction grating as a preliminary to building solar observatory.