A year´s progress in lighting

Saratoga Springs, N. Y., June 24, 1925 C. H. Sharp: There is a development mentioned in Mr. Stickney´s report which is very interesting and at the same time which might be overlooked. I refer to his mention of a practical method of realizing the reproducible primary standard of luminous intensity, — something which has been greatly needed for many years. In a paper by Dr. Herbert E. Ives, presented before the International Commission on Illumination at Geneva last summer, Dr. Ives has shown how it is possible to realize in practise a primary standard based on the brightness of a black body radiator at the melting point of platinum. The theoretical proposal of a standard on this basis is not new but was made some years ago by Waidner and Burgess. As a result of that presentation the International Commission on Illumination passed a resolution to the effect that the various national laboratories should be requested to investigate this question along these general lines with a view to proposing definitely a standard of light. It is to be hoped that this will result before many years in having a standard of light which is really fixed and reproducible from specifications.