Letter, dated 2 February, 1954, from Roy Michaelis to Mr. F. A. Stevenson. Letter typed on paper with printed letterhead. In the letter the writer mentions that he has a pipe line which has fouled up and he was inquiring if a scalebuoy would improve the problem. The second letter ( a carbon copy), dated 10/2/54, is to Mr Roy Michaelis from (name obscured). He mentions that he has thought about it but he can't see any way to help at the moment. He also says that the scalebuoy needs a steady flow of water which the hydraulic ram does not give. He also refers to some other work he has done elsewhere.sciences, instruments - general, scalebuoy, bill ashman collection - correspondence, michaelis hallenstein & co pty ltd, f a stevenson, roy michaelis