# Course of Civil Engineering: Comprising Plane Trigonometry, Surveying, and Levelling with Their Application to the Construction of Common Roads, Railways, Canals, Harbours...

Samuel J. Machen, 1842 - 301 pages

### Popular passages

Page 1 - The circumference of every circle is supposed to be divided into 360 equal parts called degrees, and each degree into 60 equal parts called minutes, and each minute into 60 equal parts called seconds, and these into thirds, fourths, &c.
Page 211 - All the interior angles of any rectilineal figure, together with four right angles, are equal to twice as many right angles as the figure has sides.
Page 180 - Mile, or jAŤ of the actual size. each inclosure, minute errors in many of which would escape observation, if not checked by comparison with the correctly ascertained whole. It is essential, in fact, to arrive at the total area of the Parish by direct admeasurement of the space included within its external boundary ; and the simplest and cheapest means by which a Survey and Plan may be made for effecting this object appear to me to be as follows : 1st.
Page 108 - I wanted to know the distance between two places, A and B, but could not meet with any station from whence I could see both objects. I measured a line CD — 200 yards ; from C the object A was visible, and from D the object B was visible, at each of which places I set up a pole. I also measured FC = 200 yards, and DE=200 yards, and at F and E set up poles. I then measured the angle AFC = 83°, ACF = 54° 31', ACD=53° 30', BDC = 156° 25', BDE=54° 30', and BED= 88° 30'.
Page 15 - ... fourth ; consequently, on the lines on the scale the distance between the first and second term will be equal to the distance between the third and fourth. And for a similar reason, because four proportional quantities are alternately proportional, the distance between the first and third terms will be equal to the distance between the second and fourth. Hence the following General Rule. The extent of the compasses from the first term to the second will reach, in this same direction, from the...
Page 11 - Pt. with which it must always be compared when used. The line of equal parts is marked from the right hand to the left with 0, 10, 20, 30, &c; each of these large divisions represents 10 degrees of the equator, or 600 miles. The first of these divisions is sometimes divided into 40 equal parts, each representing 15
Page 221 - ... for points of observation, the instrument cannot be placed exactly at the centre of the signal, and consequently the angle observed will be different from that which would have been found at the centre. The correction is generally very small, and is only necessary where great accuracy is required. The observer may be considered in three different positions with respect to the centre, viz. he is either in a line with the centre and one of the objects ; or a line drawn from the centre through his...
Page 50 - BFC, as the square of the radius is to the square of the tangent of half the angle BAC opposite to the base.
Page 198 - ... order to register all that is done relative to the survey in hand. This book every one contrives and rules as he thinks fit. It is, however, usually divided into three columns. The middle column contains the different distances on the chain-line, angles, bearings, &c., and the columns on the right and left are for the off-sets on the right and left, which are set against their corresponding distances in the middle column ; as also for such remarks as may occur, and may be proper to note in drawing...
Page 290 - As radius Is to the tangent of the latitude; So is the tangent of the sun's declination To the sine of the ascensional difference sought. This, converted into time, shows how much he rises...