A Treatise of Practical Surveying: Which is Demonstrated from Its First Principles. Wherein Every Thing that is Useful and Curious in that Art, is Fully Considered and Explained ... The Whole Illustrated with CopperplatesP. Wogan, 1795 - 319 σελίδες |
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Σελίδα 107
... Edge of its Arc : By looking along its Edge AC , to the Top of the Object whofe Height is required ; and holding it perpendicular , fo that the Plummet may neither fwing from it , nor lie on it , the Degree then cut by the Hair , or ...
... Edge of its Arc : By looking along its Edge AC , to the Top of the Object whofe Height is required ; and holding it perpendicular , fo that the Plummet may neither fwing from it , nor lie on it , the Degree then cut by the Hair , or ...
Σελίδα 108
... Edge AC , with fmall circular Holes in them ; which are useful in taking the Sun's Altitude ; requi- fite to be known in many aftronomical Cafes ; this is effected by letting the Sun's Ray , which paffes thro ' the upper Sight fall upon ...
... Edge AC , with fmall circular Holes in them ; which are useful in taking the Sun's Altitude ; requi- fite to be known in many aftronomical Cafes ; this is effected by letting the Sun's Ray , which paffes thro ' the upper Sight fall upon ...
Σελίδα 162
... Edge , and is in the Mid- dle between the two Ends . To this Center Hole on the other Side of the Frame , there are the Divi- fions of a Semicircle , or 180 Degrees ; and these again are fubdivided into Halfs , or Quarters , as the Size ...
... Edge , and is in the Mid- dle between the two Ends . To this Center Hole on the other Side of the Frame , there are the Divi- fions of a Semicircle , or 180 Degrees ; and these again are fubdivided into Halfs , or Quarters , as the Size ...
Σελίδα 163
... Edge of the Index , so as thro ' the Sights you may fee the Object in the laft Station , and by the Edge of the Index , from the Point draw a Line . Again , turn about the Index with its Edge to the fame Point , and thro ' the Sights ...
... Edge of the Index , so as thro ' the Sights you may fee the Object in the laft Station , and by the Edge of the Index , from the Point draw a Line . Again , turn about the Index with its Edge to the fame Point , and thro ' the Sights ...
Σελίδα 164
... Edge of the Index to the fecond Station , direct your Sights to the next ; draw a Line by the Edge of the Index , and lay off the next Line ; and pro- ceed fo thro ' the whole without using the Needle , as you do with the Theodolite ...
... Edge of the Index to the fecond Station , direct your Sights to the next ; draw a Line by the Edge of the Index , and lay off the next Line ; and pro- ceed fo thro ' the whole without using the Needle , as you do with the Theodolite ...
Συχνά εμφανιζόμενοι όροι και φράσεις
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Δημοφιλή αποσπάσματα
Σελίδα 13 - The circumference of every circle is supposed to be divided into 360 equal parts, called degrees; and each degree into 60 minutes, each minute into 60 seconds, and so on.
Σελίδα 88 - C' (89) (90) (91) (92) (93) 112. In any plane triangle, the sum of any two sides is to their difference as the tangent of half the sum of the opposite angles is to the tangent of half their difference.
Σελίδα 56 - ... logarithm of that number. EXAMPLE. • Required, the logarithm of 365. Answer, 2.56229. And though most tables of logarithms run but to 10000, yet by them the log. of any number not exceeding 10,000,000 may be found, and on the contrary, the number to any such logarithm, thus : 1 Find the log. of the first four figures of the given number 2. Take that log. from the log: of the number next following, and note their difference, 3. Multiply that difference by the remaining figures of the given number...
Σελίδα 91 - In the triangle ABC, there is given AB 240, the angle A 46° 30', and BC 200, to find the angle C, being acute, the angle B, and the side AC.
Σελίδα 89 - ED. that is as the sum of the two sides AB and BC, is to their difference ; so is the tangent of half the sum of the two unknown angles A and C, to the tangent of half their difference.
Σελίδα 32 - KCML, the sum of the two parallelograms or square BCMH ; therefore the sum of the squares on AB and AC is equal to the square on BC.
Σελίδα 19 - Four quantities are said to be in proportion when the product of the extremes is equal to that of the means, thus if A multiplied by D, be equal to B multiplied by C, then A is said to be to B as C is to D. POSTULATES OR PETITIONS. 1 . That a right line may be drawn from any one given point to another. 2. That a right line may be produced or continued at pleasure. 3. That from any centre and with any radius, the circumference of a circle may be described.
Σελίδα 13 - A chord is a right line drawn from one end of an arc or arch (that is, any part of the circumference of a circle) to the other ; and is the measure of the arc. Thus the right line HG, is the measure of the arc HBG.
Σελίδα 72 - ... these three proportions, for DE we put its equal be, for AE put ab, and for AD put ac, they will become AB : ab : : AC : ас, and AB : ab : : BC : be, and AC : ac : : BC : be.
Σελίδα 285 - Then if the true and magnetic amplitudes, be both north or both south, their difference is the variation ; but if one be north and the other south, their sum is the variation ; and to know whether it be easterly or westerly, suppose the observer looking...