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3. An estate may be so situated that the whole cannot be surveyed together, especially if one part cannot be seen from another. In this case, you may divide it into three or four parts, and survey each part separately, as if they were lands belonging to different persons, and af last join them together.

6. As it is necessary to protract and lay down the work as you proceed in it, you must have a scale of a proper length for that purpose. To construct such a scale, measure the whole length of the estate in chains, then consider how many inches long your plan must be, by these means you will be able to ascertain how many chains to an inch your scale must be, and make it accordingly, or cloose one ready made of the proper dimensions. Ivoiy scales, chamfered, and graduated close to the edge, are the most convenient.

7. Then trees in every hedge-row should be placed in their proper situations, but these may be taken by guess, in a rough draft, sufficiently exact, being only for ornament; excepting such as are at remarkable places, as at the ends of hedges, at stiles, at gates, &c. and these must be measured. In all the hedges, observe on which side the ditch is situated, and to whom the fences belong.

Erample by the chain and cross-staff. The measurement begins at A, fig. 9, and a direct line is measured to B, in which line every station, intended to be measured from, is carefully marked. Thus at 2* a line is measured to the right, at *3 to the left, at 4* to the right, at *5 to the left, at 6* to the right. Fron B the measurenient continues to C (the mark shows that it goes to the right), and from C to D, which completes the large triangle DBC; the correctness of the admeasurement is proved by other station-lines, as from 8* to 7*, *10 to 6*, and *l1 to 4*.

Again, CB is continued in a straight line to 12, and the measurement proceeds from 12 to 15; this line cannot be laid down on the plan till the distance from *14 to AD is measured, and the admeasurement is checked by measuring from *3 to *13, and from *5 to m. For the other lines see the following Field Book, where the stations measured from are inserted in the left-hand corner, and the stations measured to in the right ; where a hedge is crossed by a station-line nearly at right angles it is marked thus - when obliguely thus' or

, thus", when very obliquely thus 1, other appropriate marks might have been introduced, but they cannot be expressed conveniently with out having types cast for the purpose.

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Prob. 6. To survey a town or city.*

Here it will be proper to have an instrument for taking angles, as a theodolite or a plain table : the latter is a very convenient instrument, because the minute parts may be drawn upon it on the spot. A chain of 50 feet long, divided into 50 links of one foot each, will be more convenient than the common surveying chain, and an off-set staff of ten feet long will be very useful.

Begin at the meeting of two, or more, of the principal streets, through which you can have the most extensive view, and conse quently the longest station-lines. Having fixed your instrument at this point, draw lines of direction along the streets, using two men as marks, or use poles fixed on wooden pedestals, or such objects as may conveniently present themselves, viz. windows, doors, corners of houses, &c.

Measure the station-lines with the chain, and take off-sets with the staff to all remarkable places on the right and left, such as churches, public buildings, markets, halls, colleges, remarkable houses, &c. and where necessary take their dimensions.

Remove the instrument to another station in one of the lines already measured, then proceed as before, and so on till the whole is finished.

The principal streets being measured, proceed to the smaller and intermediate streets ; and, lastly, to the lanes, alleys, courts, yards, and every part requisite to be represented in your plan.

Thus, let B, fig. 10, be the first station, where a street runs off to the right, take the angle CBF, and measure the length of the street BC; when you come to the street O, on the left hand, note its distance froin B, and measure the width of it. Remove the instrumen to C, the mark which is at F to B, and that which is at C to D, and measure the angle BCD, noting the street on the right hand of C.

Measure CD, and be careful not to omit taking the dimensions of

. Emerson's Surveying, page 57, et seq.

the streets m and n on the left and right, and also their positions de move the instrument to D, the mark which is at B to C, and that which is at D to E, then take the angle CDE.

Bring the mark C to D, and E to F; then fix the instrument at E, and take the angle DEF; measure DE and EF: in measuring along EF, note the two streets on the right and left at V. Again,

Place the instrument at F, and take the angle EFE ; at F, a street goes forwards to G, and another turns to the right : measure FB, and in the way take the width and situation of the two streets at Z; having arrived at B, a part of your survey is completed, and may be laid down on paper. In a similar manner, you must proceed till the whole is finished.

Prob. 7. To cut off from a plan a given number of acres, &c. by a line drawn from any point on the side of it.

Let A, fig. 11, be the given point, from which a line is to be drawn, towards B, so as to cut off five acres 2 roods 14 perches. Draw AB, so as to cut off a quantity ABC, as near the quantity proposed as you cau judge; and suppose the true quantity of ABC, when calculated, to be only 4 A. 3 R. 20 P., which is 2 R. 34 P.=114 perches=71250 square links too little. Then measure AB, which suppose equal to 1234 links, by the half of which, viz. 617 links, let 71250 links be divided ; the quotient, 115 links, will be the altitude of the trianglo to be added, whose base is AB, therefore make BD=115 links, and draw AD, which will cut off the quantity required.

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OF

GAUGING.

The business of cask gauging is commonly performed by two instruments, pamely, the gauging or sliding rule, and the gauging or diagonal rod.

1. Of the Gauging Rule. This instrument serves to compute the contents of casks, &c. after the dimensions have been taken. It is a square rule, baving various logarithmic lines on its four sides or faces; and three sliding pieces, running in grooves in three of them.

On the first face are three lines, namely, two marked A, B, for multiplying and dividing; and the third, MD, for malt depth, because it serves to gauge malt. The middle one B is on the slider, and is a kind of double line, being marked at both the edges of the slider, for applying it to both the lines A and MD. These three lines are all of the same radius, or distance, from 1 to 10, each containing twice the length of the radius. A and B are placed and numbered exactly alike,

each beginning at 1, which may either be 1, or 10, or 100, &c. or 'l, or 01, or .001, &c. but whatever it .s, the middle division, 10, wi'l be ten times as much, and the last division 100 times as much. But i on the line MD is opposite 215, or more exactly 2150:4 on the other lines, which number 2150•4 denotes the cubic inches in a malt bushel ; and its divisions numbered retrogade to those of A and B. On these two lines are also several other marks and letters : thus, on the line A are MB, for malt bushel, at the number 2150:4; and A for ale, at 282, the cubic inches in an ale gallon ; and on the line B, is W, for wine, at 231, the cubic inches in a wine gallon : also si, for square inscribed, at •707, the side of a square inscribed in a circle whose diameter is 1 ; se, for square equal at •886, the side of a square which is equal to the same circle ; and c, for circumference, at 3:1416, the circumference of the same circle.

On the second face, or that opposite the first, are a slider and four lines, marked D, C, D, E, at one end, and rvot, square root, cube, at the other ; the lines C and D containing respectively the squares and cubes of the opposite numbers on the lines D, D ; the radius of D being double to that of A, B, C, and triple to that of E; so that whatever the first I on D denotes, the first on C is the square of it, and the first on E the cube of it; so that if D begin with I, C and E will begin with 1 ; but if D begin with 10, C will begin with 100, and E with 1000; and so on. On the line C are marked oc at .0796 for the area of the circle whose circumference is 1; and od 31 7854, for the area of the circle whose diameter is 1. Also on the line D, are WG, for wine gauge, at 17:15; and AG for ale gauge, at 18.95 ; and MR, for malt round, at 52:32 ; these three being the gauge points for round and circular measure, and are found by dividing the square roots of 231,282, and 2150 4 by the square root of 7854 : also MS, for malt square, are marked at 46 37, the nialt-gauge point for square measure, being the square root of 2150 4.

On the third face are three lives, one on a slider marked N; anc two on the stock, marked SS and SL, for segment starding and seg. ment lying, which serve for ullaging standing and lying casks.

And on the fourth, or opposite face, are a scale of inches, and three other scales, marked spheroid, or 1st variety, 2d variety, 3d variety; the scale the 4th, or conic variety, being on the inside of the slider in the third face. The use of these lines is to find the mean diameters of casks.

Besides all those lines, there are two others on the insides of the two first sliders, being continued from the one slider to the other The one of these is a scale of inches, from 124 to 36, and the other is a scale of ale gallons, between the corresponding numbers 435 and 3:61 ; which form a table to show, in ale gallons, the contents of all cylinders whose diameters are from 12 to 36 inches, their commod altitude being 1 inch,

The Use of the Gauging Rule. Prob. 1. To multiply two numbers as 12 and 25.

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