In the December number of the London Veterinarian we find an interesting communication from the pen of Mr. Tavistock, V. S., which will throw some light on the causes of disease in sheep. The substance of these remarks is as follows: "On a large farm, situated in the fertile valley of the Tavey, is kept a large flock of sheep, choice and well bred. It is deemed an excellent sheep farm, and for some years no sheep could be healthier than were his flock. About eighteen months ago, however, some ewes were now and then found dead. This was attributed to some of the many maladies sheep-flesh is 'heir to,' and thought no more about. Still it did not cease; another and another died, from time to time, until at length, it becoming a question of serious consequence, my attention was called to them. I made, as opportunities occurred, minute post mortem examinations. The sheep did not die rapidly, but one a week, and sometimes one a fortnight, or even three weeks. No previous illness whatever was manifested. They were always found dead in the attitude of sleep; the countenance being tranquil and composed, not a blade of grass disturbed by struggling; nor did any circumstance evidence that pain or suffering was endured. It was evident that the death was sudden. We fancied the ewes must obtain something poisonous from the herbage, and the only place they could get any thing different from the other sheep was in the orchards, since there the ewes went at the lambing time, and occasionally through the summer. But so they had done for years before, and yet contracted no disease. Well, then, the orchards were the suspected spots, and it was deemed expedient to request Mr. Bartlett, a botanist, to make a careful examination of the orchards, and give us his opinion thereon. The following is the substance of his report:-- "The part of the estate to which the sheep unfortunately had access, where the predisposing causes of disease prevailed, was an orchard, having a gradual slope of about three quarters of a mile in extent, from the high ground to the bed of the river, ranging about east and west; the hills on each side being constituted of argillaceous strata of laminated slate, which, although having an angle of inclination favoring drainage on the slopes, yet in the valleys often became flat or horizontal, and on which also accumulated the clays, and masses of rock, in detached blocks, often to the depth of twenty feet--a state of things which gives the valley surface and soil a very rugged and unequal outline; the whole, at the same time, offering the greatest obstruction to regular drainage. "These are spots selected for orchard draining in England; the truth being lost sight of, that surfaces and soil for apple-tree growth require the most perfect admixture with atmospheric elements, and the freest outlet for the otherwise accumulating moisture, to prevent dampness and acidity, the result of the shade of the tree itself, produced by the fall of the leaf.