acre contains 4840 square yards, 160 square perches, 10 square chains, 100,000 square links. To reduce acres, roods, and perches to links, multiply the acres by 100000, the roods by 25000, and the perches by 625. In 46A. 3R. 12P. how many square links. 46×100000=4600000 3× 25000= 75000 12× 625- 7500 4682500 square links. In measuring with the chain, the lengths of lines are generally set down in links, as integers: therefore the content is found in square links, which is readily reduced to acres by cutting off five of the figures on the right-hand, towards the left, for acres. The decimal figures are reduced to roods by multiplying by 4, and cutting off five figures as before, for decimals, which decimal part is reduced to perches by multiplying by 40, and cutting off five figures from the product. Example. Suppose the length of a rectangular piece of ground to be 573 links, and its breadth 425; required the number of acres, roods, and perches it contains. The decimal cut off amounts to more than a perch, which may be included in the contents, if the ground be of such value as to make it a matter worth claiming. The statute perch is 51 yards or 16 feet; but the Irish perch, called a plantation perch, is 7 yards or 21 feet. Hence the length of a plantation chain is 1008 inches. When an Irish chain is used, the content is found in links, as before, which is reduced to acres, roods, and perches, by the same process employed above. Hence it appears that an Irish acre is greater than an English acre in the proportion of 121 to 196, an English acre being 4840 square yards, and an Irish acre 7840 square yards, which by reduction, are to each other in the proportion of 121 to 196. To Reduce Statute Measure to Plantation Measure, and the contrary. First. To reduce Statute Measure to Plantation Measure. RULE. - Multiply the acres by 121, and divide by 196, and the quotient will give the plantation measure. EXAMPLE. - Let it be required to reduce 842 acres, statute measure, to plantation measure. Note. The first remainder, 158, is multiplied by 4, and the product divided by 196, which produces 3 roods, leaving a remainder of 44, which is multiplied by 40, and the product divided by 196, as before, giving 84 perches. 842 842 1684 842 196)101882(519 acres. 980 To reduce Plantation Measure to Statute Measure. RULE. Multiply the area in Irish measure by 196, and divide the product by 121, and the quotient gives the acreage in statute measure. EXAMPLE. Let it be required to reduce 519A. 3R. 84&p. Irish measure to English measure. Note. The acres, roods, and perches are multiplied by 196, by compound multiplication, and the product is divided by 121. Before the survey is commenced, a standard distance of 66 feet should be laid down in some convenient place, in order to ascertain the exact length of the chain every morning, and register its error, if any there be, in the field book. The chain used in the common practice of surveying generally stretches: when this is the case, a ring or two is taken off, to reduce it to the proper standard of 66 feet. Great inconvenience often arises from a neglect of this duty, as in comparing the measured distance of the principal lines with the calculation, the difference may be more than 1 link in 1000, and any lines whose difference exceeds this, ought to be re-measured if great accuracy be required, otherwise the work will necessarily twist, when plotted upon a pretty large scale; and the contents must also be affected by neglecting to note the error of the chain in the field, or correcting the chain by removing a few of the rings which connect the links. To ascertain the length of the chain, the best plan is to place two large stones firmly fixed in the ground, at the distance of about 66 feet asunder; then to cut two crosses on them, the centres of the crosses being exactly 66 feet asunder, which will always answer as a standard distance. Or, two crosses might be cut on the flag-way outside the surveyor's hall-door, at the standard distance asunder. In applying the chain to this standard distance, the difference between them, which is the error of the chain, should be measured on a brass scale divided into tenths of a link; then this multiplied by the number of chains in the measured line, will give the links to be added to, or deducted from, the number of links in the measured line, according as the chain is found to be too long or too short. This method will be found sufficiently accurate for all common purposes in the practice of surveying. EXAMPLE. After measuring the chain, it was found to be .1 of a link too long: what is the true measure of the line measured by this chain, the number of links being 32400? 32400 links=324 chains; then 324 ×.1=32.4 links; and 32400+32.4=32432.4 links, the true measure. EXAMPLE 2. - If the chain were found to be short .1 of a link, how many links in 324 chains ? 324 ×.1=32.4; then 32400-32.4=32367.6 links. To measure a Line or Distance on the Ground. To accomplish this, two persons are employed; the foremost, for the sake of distinction, is called the leader, and the hindermost, the follower. The leader is provided with ten arrows, pointed at one end, and furnished at the other end with a piece of scarlet cloth, to render them more easily seen. Having set up two poles at the extremities of the line to be measured, or one at least, at the point to be measured to, the leader takes the chain, by the ring, in one hand, and the ten arrows in the other; the follower stands at the beginning of the line, holding the chain in his hand, while the leader drags forward the chain by the other end of it, till it be stretched straight, and the leader, directed by the follower, by moving his hand to the right or left, till the follower see him exactly in a line with the pole set to be measured to, and which should be always set upright; then both of them holding the chain stretched, the leader sticks an arrow upright in the ground at the end of the chain, as a mark for the follower to come to, and advances forward another chain, being directed in his position by the follower standing at the arrow as before, as also by himself now and then at every succeeding chain's length, by moving himself from side to side, till the follower and back mark or station be in a direct |