The method of constructing the cells was described in the SCIENTIFIC AMERICAN SUPPLEMENT, No. 462, for Nov. 8, 1884, page 7371.
Cells No. 23 and No. 129 are now in possession of Prof. W. Gryllis Adams, of King's College, London; Dr. Werner Siemens has No. 25, and Prof. George F. Barker, of Philadelphia, has No. 26.
No. 24 was measured with a bridge multiplier of 6 to 1.