No. 7. Draining — Who shall decide, when Doctors disagree ? 



237 



shape of rain, is instantly absorbed, and passes 

 through the sand, or gravel, to some outlet at 

 a lower level" (then why, in the name of 

 common sense, drain !); " in the latter case, 

 on the contrary, v^'ater, whether springing 

 from below or falling upon the surface as rain, 

 must either run slowly off over the surface, 

 however great the distance, or, in the event 

 of a horizontal surface, must remain stagnant 

 until evaporated by the sun, or absorbed by 

 the atmosphere" (then, in the name of com- 

 mon sense, drain) ; " on such a subsoil, a suf- 

 ficient depth of active soil can never be long 

 maintained, for grain ; if trenched and enriched 

 by lime and dung, it will bear but scanty 

 crops. Some soils, again, are incumbent on 

 subsoils partially pervious to water — such, 

 by judicious management, produce some- 

 times good crops, in favourable seasons, but 

 when much rain prevails, they are neither 

 large or of good quality ; these are unfit for 

 wheat, as the alternate frosts and thaws of 

 winter, acting upon the water in the soil, are 

 sure to throw out the plants. But on those 

 soils incumbent on open rock, especially on 

 whin, or green-stone, which is very open, 

 from its many fissures, the land is uniformly 

 fertile" (then why drain ?). " But," he ob- 

 serves, " the drains should be run parallel to 

 each other, and at regular distances, and 

 should be carried throughout the whole field, 

 without reference to the wet or dry appear- 

 ance of portions of the field ; as uniform and 

 complete dryness is the object ;" directing 

 that the drains, in a stiff", strong till, be run 

 within ten or fifteen feet of each other ; if in 

 a lighter, and more porous subsoil, from eigh- 

 teen to twenty-four feet will be near enough, 

 but in very open soils, forty feet may be suf- 

 ficient. He says; " a very important advan- 

 tage of having the drain down the steep, is 

 the prevention of any lodgement of mud or 

 sand, the current having force, from the de- 

 clivity, to carry them along to the main 

 drain ;" but, he afterwards adds ; " indeed, the 

 water passing into the drains by filtration, 

 being perfectly pure, has no sediment to de- 

 posit, for even during the heaviest rains, the 

 water passing from a properly made drain, 

 has merely a milky tinge." Now how is this 

 to be understood 1 If the water is perfectly 

 pure, it will have no tinge at all, and whe- 

 ther, at any time, milky or inky, must depend 

 on the strata through which it has passed ; 

 but whatever the colour, if it has any tinge, 

 there must be sediment. In forming under- 

 drains, it has ever been the custom to lead 

 them by as easy a descent as would be pru- 

 dent, to prevent the possibility of washing, 

 lest they might thus become choked, and 

 blow up ; and even Mr. Smith himself seems 

 to admit the danger of this, for he says, " it 

 is quite necessary to fill the drains, which 



are carried down the slope, with stones of a 

 small size, or witti danders or gravel, to 

 prevent the current of water from cutting or 

 running the bottoms of the drains," and by 

 which they would, of course, become choked, 

 and blow up. 



Any how, the subject is one of great im- 

 portance, and ought to be examined into, with 

 the view to establish some system for adop- 

 tion, whenever necessary ; for there is no im- 

 provement so great, profitable, or lasting, as 

 draining, when properly executed. 



M. C. 



Wilmington, Delaware. 



Mr. Smith has, within fifteen years, formed 

 on his land under-drains to the extent of one 

 hundred miles in length ! 



For the Farraer8' Cabinet. 

 Observer — No. 34. 



"WHO SHALL DECIDE, WHEN DOCTORS DISAGREE?" 



I PERCEIVE, by the last Cabinet, that a 

 Miss Morris has once more discovered that 

 the wheat-fly {cecidomya destructor) deposits 

 its eggs in the grain previous to its being 

 harvested — that when the grains vegetate, 

 and not till then, the eggs are hatched — that 

 the larvee proceed thence to occupy their 

 usual position in the sheaths of the blades — 

 that they remain in the larva state and feed 

 upon the plant until the beginning of June, 

 when they pass to the chrysalis, or pupa, or 

 flaxseed state — and that soon after they 

 emerge in the fly, and deposit their eggs in 

 the ripening ears, 



I should not have noticed this discovery — 

 merely as such — for it has been made per- 

 haps forty-nine times before — but when I 

 consider that it is opposed by the every-day 

 experience of thousands of observant farmers, 

 and that it comes into the world endorsed by 

 the imposing names of Thomas Nuttal, Isaac 

 Lea, and Benjamin H. Coates, M. D., with 

 the American Philosophical Society for its 

 godfather, I may confess my fears for the 

 consequences. 



Doctor Coates does not pretend to a per- 

 sonal acquaintance with the cecidomyia de- 

 structor, nor does he happen to know that 

 any person, except Thomas Say and Miss 

 Morris, has ever observed its habits. Hence, 

 by taking what they have communicated as 

 the sum total of our knowledge of that mis- 

 chievous insect, he has been led inadvertently 

 into error. 



The Doctor observes, that " Miss Morris's 

 observations and inferences agree very well 

 with what we know of many insects." What 

 insects'? Why, "the animal that destroys 

 the luxuriant shoots of the parsley-leaved 

 elder, passes its larva-existence in the pith 



