Diagram of the W. & L. E. Gurley Solar Attachment
Image Source: "A Manual of the Principal Instruments Used in American Engineering and
Surveying, Manufactured by W. & L. E. Gurley, Troy, N.Y.," Forty-Second Edition, 1908, p. 72.
Diagram of the W. & L. E. Gurley Solar Attachment
Image Source: "A Manual of the Principal Instruments Used in American Engineering and
Surveying, Manufactured by W. & L. E. Gurley, Troy, N.Y.," Forty-Second Edition, 1908, p. 72.