Summary: A NEW loop galvanometer made by the firm of Messrs. Carl Zeiss, of Jena, possesses several novel features. Although with its most insensitive arrangement it is capable of detecting a microampere, it is not easily damaged mechanically, and with a suitable field stand (Fig. i) it can be used for taking out-door observations. In principle the instrument utilises the action of a magnetic field acting on a current carried by a light loop of metal foil. The magnetic field is produced by two strong permanent magnets the unlike poles of which face one another (Fig. 2).