Discussion on "Recent developments in the measurement and control of surface roughness" at the Western Section of the Institution

CAPTAIN BURGOINE : First of all, is the instrument Mr. ^ described yet developed to any sort of practical condition, so that one might purchase it to use in a factory ? If it is not a secret, what material is used for the stylus passing over the surface ; what is the form of the stylus ; how long does it wear ; and what is the effect of drawing it over a soft material such as bronze ? Does it not scratch, and is there no tendency to damage a really good surface ? The paper seems to be really divided in two parts. One part deals with means of detecting, measuring, and recording surface roughness ; the other wibh the advantages of colloidal graphite. These two subjects do not seem to be such as really should be embodied in a single paper. I should like to know whether the author has any experience of the use of colloidal graphite as a lubricant during the actual machining or finishing. I have heard that certain firms in America use it in small quantities during honing, with, it is claimed, good results.