or downwards 



506 DRAINAGE 



nearly a foot of the depth of the ditch and are more 

 likely to become obstructed, especially if placed near 

 the surface, than are tile drains. The throats or open- 

 ings of stone drains are irregular in size, while those of 

 tile drains are smooth and uniform in size, and are, 

 therefore, most desirable. Years ago, various flat-bot- 

 tomed tiles (Fig. Titi) were used, but the only style in 

 general use at present is the cylindrical unglazed tile- 

 shown in Fig. 737. 



In some sections drains are placed 200 to 300 feet apart, 

 and serve their purpose well. In others they should not 

 be placed farther apart than from 20 to 30 feet. Where- 

 ever the subsoil is composed of 

 through which the water moves 

 with diflBculty, the narrower in- 

 tervals are necessary. In some 

 instances the surplus water in 

 the subsoil is underpressure by 

 reason of water which finds its 

 way into it from higher levels, 

 and if this is not removed, the 

 water has a constant tendency 

 to rise to the surface. In many 

 such cases drains placed at wide 

 intervals may serve to relieve 

 the pressure and drain the land. 

 Since sub-drains are designed 

 to be permanent, arc expensive 

 to construct and (lilllrull to re- 

 pair, the prill. Ml, Ics ,,i' .lr;iinage 

 should be w.ll iiinli i-rM.Ki, and 

 the work should Im uml. itakcn 

 only aftera mu.st r;ii-< lul jiisitcc- 

 tion of the land luui aftir tin- 

 fundamental priuciplrs c,f till' 

 subject have been ni.i>ter(cl. 



Mains and sub-mains slji.ulil 

 be avoided so far as possible, 

 since they greatly increase cost, 

 tend to become obstructed, and 

 are often unnecessary. The 

 three long mains in i'ig 738 are 

 not drains, strictly speakmg, 



may be more outlets to construct and maintain than is 

 desirable; if so, the system might be modified by con- 

 structing a sub-main, one side of which will serve also 



tile. 



since the land may be as fully drained without them, as 

 shown in Fig. 739 ; therefore, they only serve to conduct 

 the water of the drains proper. Tiles of 3 to 4 and 5 inches 

 diameter should be used when the drains are infrequent 

 and the flow of water considerable. Smaller ones, 2 to 3 

 inches in diameter, will suffice when the intervals be- 

 tween the drains are narrow. Drains should have as 

 uniform a fall as possible, and no abrupt lateral curves 

 or sharp angles should occur as are seen in many places 

 in Pig. 738. If the drain has a rapid fall in its upper 

 reaches, as is often the case, and but slight fall in the 

 lower, a silt basin should be constructed at the point 

 at which the rapid chan^fs into Hip sliL'ht fall, if olistrnot- 



should be placed, li' l"r. Ilir |i|aiiliriL' .i.nirs. (Irihanl 

 lands may be draiii*il in iIm' -■ln■in^^ t;iiln\\ ..J in the sum- 

 mer, and planted in thr fall nr tlir fclluwiiig .'ipriiig. 

 Drains placed at frequent intervals because of the te- 

 nacity of the soil should be comparatively shallow, for 

 If placed deep or at wide intervals, the water will be too 

 long reaching them. If drains are placed at wide inter- 

 vals they should be at least 3K feet deep to be most efli- 

 cient. If the parallel system is adopted (Fig. 739), there 



Improper method of 



as a drain, and but one outlet will be required (Fig. 740). 

 Drains through which water runs for the greater part 

 of the year are likely to become obstructed by roots, if 

 water-loving trees, such as the willow, soft maple and 

 elm, are allowed to grow near them. If floating silt is 

 present the joints of the tiles should In- jiiMtrrtrd f.ir 

 two-thirds of their upper circumferenin^ iiv a narmw 

 strip of tarred building paper, or collars s I m i , i < i i , 1 1 , ,, I . 

 Stone drains should receive a liberal cov. unu il ,,tiau 

 before they are filled. i. j.. K,jHtKTs. 



DEEEE, HENRY A. Seedsman, and founder of one 

 of the oiliest American horticultural establishments; 

 was burn in Philadelphia, Aug. 24, 1818, and died there 

 Dec. 22, 1873, at the age of fifty-five. His parents were 

 Frederick Dreer, of Hanover, and Fredericka Augusta 

 Nolthenius, of Grossakenheim, Germany. They were 

 married in America. The Nolthenius family emigrated 

 to the United States in the last decade of the eigh- 

 teenth century, and were closely connected with the 

 Lutheran Church. Henry A. Dreer's education was 

 largely in German, and obtained in Philadelphia. He was 

 fond of gathering seeds ami plants in the country, and 

 would bring tin in linmn t.i mltivati-. He was trained in 

 his father's buMii. ■, ^. Unit. .la. III. in. t -maker. In 1838, at 

 the solicitati.ni ..f a In. ml, ],<■ L.-traii as a florist in a 

 small way, m-ar I'n.iit ami ( 'lustir Sts. About 1870 he 

 removed to Seventh and Chestnut. In 1869 he enjoyed 

 a 5 months' trip to Europe, where he met business cor- 

 respondents of 30 years' standing. He w; 

 .Tune 22. 1847, to Mary Leavenworth, of Re 



married 



