THE FARMER'S MAGAZINE, 



381 



two yards. The lower portion of small drains exceeding 

 ten chains in length should be laid with three-inch 

 pipes, and towards the junction with main drains ex- 

 ceeding twenty chains, especially in flat ground, should 

 be laid wiih pipes of four inches bore. 



Jn making an estimate for the size of pipes to be used 

 in main drains, the rainfall of the district in which 

 draining is about to be undertaken, the fall of the 

 drains, and the fxtent of ground from which water has 

 to be discharged, must have attentive consideration. 



As to the first of the above-mentioned topics, that of 

 amount of rainfall, it varies on an annual average very 

 greatly in different localities in the British Islands. In 

 some localities the average annual rainfall for a number 

 of years has been observed to have scarcely exceeded 

 20 inches in depth ; whilst in others it has amounted to 

 GO inches, or three times the quantity. Let the aggre- 

 gate quantity of rain falling in any district over a 

 lengthened period be what it may, one inch failing 

 within twenty. four hours would almost be considered a 

 phenomenon in the wettest district, and one-half or 

 one-third that depth falling in other places in the same 

 time would be equally remarkable. For purposes of 

 the cs imate now being discussed, the greatest rainfall 

 need not be provided for, as it is well known that a great 

 portion of the actual rainfall in a district is disposed of 

 by various other sources than drains, even when these 

 are most effective. Amongst the means by which water 

 is carried from the soil, otherwise than by filtration by 

 drains, the following may be adverted to : 



Evaporation from the surface by the atmosphere, the 

 power of which is influenced by its heat, its state of 

 dryness, and by its motion. The atmosphere has most 

 power in removing water from the soil during June, 

 July, and August, and least during December, January, 

 and February. 



The nature of the soil in its power of retaining water 

 in absorption. The kmds of soil most retentive of 

 water are peats, and those containing a large proportion 

 of fibrous vegetable matter in their composition ; and 

 the least are those of an arenaceous kind. 



All plants remove a great portion of water from the 

 soil during the active state of their vegetation, and the 

 time when this is most powerfully in action is during 

 April and May. 



Taking all causes into account which may dispose of 

 rainfall by other means than by filtration, a provision 



for more than one-tbird of the heaviest falls in the 

 district need not be provided for to be carried off by 

 drains in twenty-four hours. 



The velocity of water running in covered drains is 

 found by the same rule as previously given for open 

 water- courses, and which is to multiply the square- 

 root of the product of the rate of fall of drain per mile 

 in feet by the hydraulic depth, or radius of the section of 

 the drain in feet by 82-5, and the product is the velocity 

 of the current of water in feet per minute. For drain 

 pipes, the radius, or one-half the diameter of the bore, is 

 to bo considered the actual depth, and one-half the 

 radius, or one-fourth the diameter of the bore, the 

 hydraulic depth or radius of the section. 



The following are the hydraulic depth, in feet of tile- 

 pipes from 1 to 12 inches diameter of bore, for finding 

 the velocity by the foregoing rule ; and of the semi- 

 circular area of the section of the pipes in square feet, 

 for finding the discharge in cubic feet, when such area is 

 multiplied by the velocity in feet per minute. 



Diameter Hydraulic Semicircular 



of bore depth area in 



in inches. in feet. squnre feet. 



The writer has constructed tables for finding the re- 

 sults of all the rules for calculations required in the 

 execution and estimating the cost of draining, if not in 

 all cases by inspection, at any rate by the addition of a 

 few lines of figures, which probably may, at some 

 future time, be published, with an extension of the 

 present article in the form of a book. 



So well adapted are tile-pipes for the ducts of drains, 

 that they should supersede the use of every other 

 material for the purpose, wherever they can be ob- 

 tained at a reasonable cost, and, from the facilities of 

 transport by railway communication in every direction 

 throughout the United Kingdom, will in very few 

 localities not be the case. 



Newcastle-upon-Tyyie, March, 1861, 



THE PROGRESS OF THE STEAM PLOUGH. 



A vngue notion has got abroad that steam-power, 

 when harnessed and worked as it should be, will ac- 

 complish results in fitld-labour incomparably greater 

 than any yet produced by steam ploughs or farm 

 locomotives. Look at the factories, people say : 

 steam does not barely surpass the former rate of 

 production by hand, but multiplies it by tens 

 and hundreds. One woman now manages seven 

 hundred spindles, each twisting at the speed of 



five thousand revolutions per minute throughout a 

 ten-hours' day, instead of working only one spindle at 

 a time, with a slower motion and frequent rests, as she 

 was formerly obliged to do. Look, again, at the steam 

 road, with its load of a hundred tons flying along at 

 thirty miles an hour, compared with the horse road, 

 with its load of two or three tons dragged three niileS 

 in the same time. Steam must equal results like these 

 in agriculture, if it be worth anything ; and no Fowler, 



