A.C. Switchboard instruments
Ltd. A. Reyrolle and Co. · Journal of Scientific Instruments · 1937
In order to keep readers of the Yournal in touch zcith the latest developments in scientific instruments and light machine tooh, the Editor zcould be glad i f all manufacturers of such instruments or tools would keep him informed of all new devices or important improoements in their productions as soon as they appear, either by sending him catalogues, pamphlets or circulays concerning them, or in the case of important developments, by letting him have concise special descriptions of their construction and performance.