Autograph letter signed to Charles Bright and Latimer Clark

1865. Very Good. Matthiessen, Augustus (1831-70). A.L.s. to Charles Tilston Bright and Latimer Clark. [London], April 20, 1865. 1- pp. 176 x 112 mm. Small holes in lower corner, tremains of mounting present. Provenance: Latimer Clark. Between 1862 and 1865 Matthiessen participated in the British Association's Electrical Standards Committee. His letter mentions some of the standard units that he manufactured in 1865 for the committee: "They are made of the Platinum silver alloys and are adjusted to 0.01 percent accuracy. With the aid of this and two small B. A. units the ratio for 100 B. A. units and so on, can be accurately produced." Origins of Cyberspace (truncated) 176. . (Inventory #: 40741)