1860. 



NEW ENGLAND FARRIER. 



61 



Nothing appertaining to drainage has been 

 done so blindly, either in England or in this coun- 

 try, as the selection of the size of pipe for sub- 

 main and main drains. 



The result of an error in the size of pipe re- 

 quired is sometimes only extravagant, at other 

 times it is mischievous, for the destruction of the 

 work may be caused by it. If the size of pipe 

 used is larger than is requu'ed, the extra cost is 

 thrown away — but if smaller, then the pressure of 

 water, accumulated from lateral drains, and flow- 

 ing into a submain or main drain too small to 

 convey it away, may cause the pipe to "blow," or 

 burst. 



We are liable to have, at any time in New Eng- 

 land, a rainfall of 3 inches vertical depth. 



It has been found, from various long and care- 

 ful observations, that 50 per cent, of this rainfall 

 is water of drainage, from land in ordinary con- 

 dition in the northern States. 



From a thoroughly drained field, the percentage 

 of water of drainage will bo greater than this, but 

 not over 661 per cent., except under extraordina- 

 ry circumstances. We have, therefore, assumed, 

 in making up these tables, that it is necessary to 

 provide for the discharge of water falling upon a 

 strip of land forty feet in width, to the depth of 

 two inches, and running off in forty-eight hours. 



The quantity of discharge is given for a straight 

 pipe running full, but a full pipe cannot perform 

 the office of drainage and an allowance of 15 per 

 cent, of the area has been made, to allow of the 

 entrance of water all along the line of the drain. 

 All drains are liable to curvature, and a greater 

 part of the drains in ever)' system must be curved, 

 to some extent, at their confluence with other 

 drains. A well laid drain, turning by a gentle 

 curve to flow at right angles with its former course, 

 will discharge about 10 per cent, less water than 

 when running straight, — an allowance has there- 

 fore been made for this. 



In a thoroughly pulverized soil, the space occu- 

 pied by air is about 25 per cent, of the entire bulk, 

 80 that such a soil, di-ained to the depth of 3 or 4 

 feet, would receive the largest rainfall of which 

 we have any record, without filling the soil, and 

 running ofl" over the surface. Such pulverization 

 can only occur under the most constant cultiva- 

 tion and thorough drainage ; but most soils, well 

 drained and subsoiled, Avill, after the drains have 

 acted for two or thi-ee years, receive the largest 

 rainfall without surface-washing. 



The tables can only be used to provide for 

 water falling on the surface occupied by the drains. 

 If the drained field occupies such a position that 

 surface water flows from other fields into it, the 

 size of pipes must be sufficiently increased to pro- 

 vide for it, and if the water of springs would find 

 outlet through the drains, a similar provision must 

 be made for it., Of the necessary increase in size 

 for these conditions, only an experienced and 

 competent person can judge ; but the tables are 

 still very useful under these circumstances, for 

 the relative size of pipe required remains as be- 

 fore, and the proper place to make a change from 

 the size of pipe being used to the next larger, can 

 be accurately determined from them. 



The areas used in these tables, and given under 

 each size of pipe, are taken by actual measure- 

 ment from pipe manufactured in New England. 

 The Ih, 2, 3, 4, and 5 inch sizes, are common sole- 



tile pattern. The 8 inch size is round bore, 8 

 inches in diameter. 



The left hand or first cohimn, shows the fall in 

 one hundred feet given in feet and inches. The 

 second gives the number of gallons of water the 

 pipe would dischai'ge in twenty-four hours if laid 

 at that inclination. The third shows what length 

 of pipe of that size may be used to convey water 

 of rainfall, before it will be necessary to take the 

 next larger size. 



In seeking the necessary size of pipe for a cer- 

 tain position, the aggregate length of all the di-ains 

 above it, from which water would flow into the pipe 

 at this point, must be taken from the length allowed 

 by the table, and the remainder will show what 

 length of pipe may be used from that point for- 

 ward, as far as the fall continues the same. 



11 INCH DRAIN PIPE AREA, 1.77 INCHES. 



Fall, 

 ft. in. 

 0.3 

 0.6 

 0.9 

 1.0 

 1.3 

 1.6 

 1.9 

 2.0 

 2.3 

 2.6 

 2.9 

 3.0 

 3.3 

 3.6 

 3.9 

 4.0 

 4.3 

 4.6 

 4.9 

 5.0 



Discliarge. 

 5631 

 8248 

 10231 

 12055 

 13800 

 15148 

 16655 

 17924 

 19113 

 20303 

 21334 

 22444 

 23151 

 24268 

 25061 

 26013 

 26806 

 27441 

 28234 

 28947 



Length. 

 169 

 247 

 307 

 362 

 414 

 454 

 500 

 538 

 573 

 609 

 640 

 673 

 694 

 728 

 752 

 780 

 804 

 823 

 847 

 868 



Fall, 

 ft. in. 

 5.3 

 5.6 

 5.9 

 6.0 

 6.3 

 6.6 

 6.9 

 7.0 

 7.3 

 7.6 

 7.9 

 8.0 

 8.3 

 8.6 

 8.9 

 9.0 

 9.3 

 9.6 

 9.9 



10.0 



Discharge. 

 29705 

 30454 

 31168 

 31723 

 32516 

 33151 

 33706 

 34340 

 34975 

 35609 

 36154 

 36878 

 37354 

 37989 

 38464 

 38940 

 39495 

 39971 

 40447 

 40923 



Length. 



891 



913 



935 



952 



975 



995 

 1011 

 1030 

 1049 

 1068 

 1085 

 1106 

 1121 

 1140 

 1154 

 1168 

 1185 

 1200 

 1213 

 1228 



2 INCH DRAIN PIPE AREA, 2.98 INCHES. 



Fall, 

 ft. in. 

 0.3 

 0.6 

 0.9 

 1.0 

 1.3 

 1.6 

 1.9 

 2.0 

 2.3 

 2.6 

 2.9 

 3.0 

 3.3 

 3.6 

 3.9 

 4.0 

 4.3 

 4.6 

 4.9 

 5.0 



Discharge. 

 10575 

 15528 

 20080 

 ■ 22891 

 25970 

 28915 

 31459 

 33868 

 36010 

 37884 

 39758 

 41632 

 43373 

 44979 

 46585 

 48058 

 49531 

 50869 

 52342 

 53814 



Length. 

 317 

 465 

 602 

 687 

 780 

 867 

 944 

 1016 

 lOSO 

 1137 

 - 1193 

 1249 

 1301 

 1349 

 1398 

 1442 

 1486 

 1526 

 1570 

 1614 



Fall, 

 ft. in. 

 5.3 

 5.6 

 5.9 

 6.0 

 6.3 

 6.6 

 6.9 

 7.0 

 7.3 

 7.6 

 7.9 

 8.0 

 8.3 

 8.6 

 8.9 

 9.0 

 9.3 

 9.6 

 9.9 



10.0 



Discharge. 

 55019 

 56492 

 57696 

 5S901 

 60106 

 61310 

 62382 

 63453 

 64667 

 65728 

 66799 

 67870 

 68941 

 70012 

 71083 

 72020 

 73091 

 74028 

 74965 

 75902 



Length. 

 1650 

 1695 

 1731 

 1767 

 1803 

 1839 

 1872 

 1904 

 1940 

 1973 

 2004, 

 2036 

 2068 

 2100 

 2132 

 2160 

 2193 

 2221 

 2249 

 2277 



3 INCH DR.4IN PIPE AREA, 6.11 INCHES. 



Fall, 

 ft. in. 

 0.3 

 0.6 

 0.9 

 1.0 

 1.3 

 1.6 

 1.9 

 2.0 

 2.3 

 2.6 

 2.9 

 3.0 

 3.3 

 3.6 

 3.9 

 4.0 

 4.3 

 4.6 

 4.9 

 5.0 



Discharge. 



24687 



36482 



45534 



53215 



60072 



66606 



72142 



77628 



82291 



86680 



90794 



95183 



98749 

 102589 

 106155 

 109447 

 112738 

 116030 

 119047 

 122339 



Length. 

 740 

 1094 

 1366 

 1596 

 1S02 

 2000 

 2164 

 2329 

 2469 

 2G00 

 2724 

 2855 

 2962 

 3078 

 3184 

 3283 

 3382 

 3481 

 3571 

 3670 



Fall. 



ft. in. 

 5.3 

 5.6 

 5.9 

 6.0 

 6.3 

 6.6 

 6.9 

 7.0 

 7.3 

 7.6 

 7.9 

 8.0 

 8.3 

 8.6 

 8.9 

 9.0 

 9.3 

 9.6 

 9.9 



10.0 



