A treatise on land-surveying; comprising the theory developed from five elementary principles; and the practice with the chain alone, the compass, the transit, the theodolite, the plane table, &cIllustrated by four hundred engravings, and a magnetic chart . rivances for overcoming the obstacles which may bemet with, will be explained in the following chapter. It will oftenbe convenient to measure the minor lines along roads, lanes,paths, &;c., although they may not lie in the most desirable direc-tions. Steeples, chimneys, remarkable trees, and other objects ofthat character, may often be sigh
A treatise on land-surveying; comprising the theory developed from five elementary principles; and the practice with the chain alone, the compass, the transit, the theodolite, the plane table, &cIllustrated by four hundred engravings, and a magnetic chart . rivances for overcoming the obstacles which may bemet with, will be explained in the following chapter. It will oftenbe convenient to measure the minor lines along roads, lanes,paths, &;c., although they may not lie in the most desirable direc-tions. Steeples, chimneys, remarkable trees, and other objects ofthat character, may often be sighted to, and the hne measured to-wards them, wnth much saving of time and labor. The pouit wherethe measured lines cross one another should always be noted, andthey wiU thus form a very complete series of tie-lin«s.* A view of the district to be surveyed, taken from some elevatedposition, will be of much assistance in planmng the general direc-tion of the lines to be measured. (134) Inaccessible Areas. A combination of offsets andtie-hnes supplies an easy me-thod of surveying an inacces-sible area, such as a pond,swamp, forest, block of houses,&c., as appears from the fi-gure ; in which external bound-ing lines are taken at will and Fig. * To fiud the exact point of intersection :/ these lines, which are only visuallines, (explained in Art. (19),) three persons are necessary: one stands at soncepoint of one of the lines and sights to some other point on it; a second does thegame on the second line ; by signs they direct, to ri^ht or left, the movements of athird person, who holds a rod, till he is placed in ooth of the lines and thus attlieir intersection, on the principle of Art. (11). 94 €HAL\ SURVEYING. [part II. measured,and tied by tie-lines* measured between these lines,prolonged when necessary, as in Art. (101), while oSsets fromthem deteraiine the irregularities of the actual boundaries of thepond, &c. These offsets are insets, and their content is, of course, to
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectsurveying, bookyear18
