Surveying and Levelling Instruments, Theoretically and Practically Described. / For construction, qualities, selection, preservation, adjustments, and uses; with other apparatus and appliances used by civil engineers and surveyors in the field.

by William Ford Stanley

Fig. 185.—Stanley's light micrometer transit.

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An example of a more refined micrometer transit is shown at Fig. 186. This instrument was designed by Dr. E. Deville, LL.D., Surveyor-General of Canada, and is arranged for latitude determination by Talcott's System, and general geodetic work.

Fig. 186.—Dr. Deville's transit.

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It has a 6-inch horizontal circle reading by micrometers to 5 seconds of arc, and a 4-inch vertical circle reading by vernier to 1 minute, with zenith spirit level graduated to 2 seconds of arc, detachable and interchangeable with a small level for ordinary use. The telescope is 14 inches solar focus with large object glass so that observations may be taken of stars up to the sixth magnitude; it has a revolving micrometer diaphragm and electric illumination to micrometers, to diaphragm both front and back, and to zenith spirit level, it has also a rheostat for regulating the amount of light, and a dynamo generator for supplying the current.

Fig. 187.—Stanley's patent universal transit theodolite.