. Canadian engineer. tii)ii:il field work ontheir part. A precise levelling party consists of seven men, thechief or leveller, recorder, two rodmen, umbrellaman, cookand a railway employee, usually a section man, to pilot thehand-car. Camps are made at the stations along the line,the distance apart varying from 10 to 20 miles. Thelevelling is carried continuously forward, day by day,through the camp and to a point about half-way to wherethe next camp ahead will be. General instructions issued to levellers are: All linesare to be levelled twice, in opposite directions, called for-ward and backw
. Canadian engineer. tii)ii:il field work ontheir part. A precise levelling party consists of seven men, thechief or leveller, recorder, two rodmen, umbrellaman, cookand a railway employee, usually a section man, to pilot thehand-car. Camps are made at the stations along the line,the distance apart varying from 10 to 20 miles. Thelevelling is carried continuously forward, day by day,through the camp and to a point about half-way to wherethe next camp ahead will be. General instructions issued to levellers are: All linesare to be levelled twice, in opposite directions, called for-ward and backward levelling. Backward shall in everyrespect be independent of forward le\elling and the sameturning points shall not be used. If the forward levellingis made in the forenoon, the backwand—over the samesection—should be made in the afternoon, it being desir-able to secure as much difference in atmospheric condi-tions between the forward and backward measurements A LB£ft TA 3 ASK A T C H £. V\/A N MA N IT O B A. Fig. 4.—District Covered by Levels Run from of the United States Coast and Geodetic Survey at Stephen, Minn can be found, and in no case to run more than eight mileswithout establishing one. To comply with the latter re-quirement it has been found necessary to erect, at certainpoints, concrete piers, specially for bench marks. Thesepiers are 6 feet 3 inches high, 9 inches square at the topand 15 inches square at the bottom, resting on a concretefooting. The whole pier is buried to within about 9 inchesof the top, and the copper bolt built in, near the groundsurface, having been previously stamped and piers are usually built on the railway right-of-way,within 3 or 4 feet of one of the fences and on fairly levelground, where they will not be exposed to danger fromfuture alterations in the railway grade. Temporary bench marks are placed at intervals of imile or thereabouts. They consist usually of spikes,driven horizontally into telegraph poles, a
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