A treatise on land surveying [ed.] by W. Galbraith1849 |
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Common terms and phrases
A R P acres altitude angle axis azimuth back sight bearing was taken Bearings and Distances Bonnyton calculation centre chain circle column compasses computed corner correct cosec decimals degrees divided division draw edge equal error eye-sketch feet fence field-book figure formula give Goatfell ground horizontal inches Inchkeith Indian ink INNERLEITHEN insert intersect latitude length limb logarithm longitude mark mean measuring that line meridian method move it parallel multiplied needle observations offset parallax parallel ruler perches perpendicular plant the instrument Plate plotting pole placed protracted protractor put one foot radius reduced right ascension river road roods scale screw sextant side spherical excess square links ST MARY'S LOCH staff station sun's survey surveyor take a back take a bearing telescope theodolite trapezium triangle Trigonometrical Survey turn the telescope vane vernier vertical wide zenith-distance
Popular passages
Page 476 - The level, which is shown under and parallel to the telescope, is attached to it at one end by a joint, and at the other by a...
Page 238 - or nearly; that is, the difference between the true and apparent level, is equal to the square of the distance...
Page 194 - To find the Area of a Triangle when the Three Sides are given. Rule. — From half the sum of the three sides subtract each side separately. Multiply the half sum and the three remainders together, and extract the square root of the product.
Page 476 - ... parallel to the optical axis of the telescope, or line of collimation ; the screw, g, at the opposite end, is to adjust it laterally, for true parallelism in this respect. The telescope has two collars, or rings, of bell metal, ground truly cylindrical, on which it rests in its supports...
Page 480 - Now release the upper plate, and move it round by hand till the telescope is directed to the second object, whose angular distance from the first is required...
Page 498 - ... to the horizon. The levelling of the axis, as it is called, is therefore one of the most important adjustments of the instrument, and is effected by the aid of a spirit-level, E, which is made for this purpose to stride across the telescope, and rest on the two pivots. The standards, DD, are fixed by screws upon a brass circle, F, which rests on three screws...
Page 5 - ... and Minuit was drowned. MINUTE, a unit of time equal to 60 seconds. There are 60 seconds in one minute and 60 minutes in one hour. MINUTE, in angular measurement, the sixtieth part of a degree in the sexagesimal system. In this system the circumference of a circle— one complete revolution— is divided into 360 equal parts called degrees, the degree is divided into 60 equal parts called minutes, and the minute is divided into 60 equal parts called seconds. The symbol for the degree is °, the...
Page 486 - ... with the load it carries, is prevented from pressing too heavily on its bearings, by two friction rollers on which it rests, one of which is shown at e. A spiral spring, fixed in the body of each pillar, presses the rollers upwards, with a force nearly a counterpoise to the superincumbent weight; the rollers on receiving the axis yield to the pressure, and allow the pivots to find their proper bearings in the Y's, relieving them, however, from a great portion of the weight. The telescope, K,...
Page 478 - ... of a distant object; then turn the telescope half round in its Y's till the level lies above it, and observe if the same point is again cut by the centre of the wire ; if not, move the wire...
Page 499 - ... has five vertical and two horizontal wires. The centre vertical wire ought to be fixed in the optical axis of the telescope, and perpendicular to a line drawn through the pivots of the axis. It will be evident, upon consideration, that these wires are rendered visible, in the day-time, by the rays of light passing down the telescope to the eye ; but at night, except when a very luminous object (as the moon) is observed, they cannot be seen. Their illumination is therefore effected by piercing...