Scheme of a Succession of Field Crops. 13 



small piece between 25° and 36° will be easily found. The 

 full height at 36° above the level of the instrument being 

 36 feet 3f inches, we have only to deduct the height at 25°, 

 which leaves a difference of 1 3 feet Of inches for the leno-th of 

 the piece. Opposite to 45° on the table I find 50 feet, beino- 

 the height of the summit of the tree above the instrument, 

 and which, added to the 6 feet below that level, gives the 

 height of the tree, or 56 feet. The legs of the instrument, 

 I should remark, are attached to it with thumbscrews. The 

 single leg has a motion along, and the other two across the 

 instrument, by which means it can be fixed to any level. A 

 telescope attached to the quadrant with cross hairs, and a 

 spirit level sunk in along the table, might be useful accom- 

 paniments, but are not indispensable. An index or arrow is 

 placed at the off side of the slider, to mark the space travelled 

 over in taking the diameter. 

 Annat Garden, Feb. 24. 1826. 



An instrument for effecting the same objects as that of Mr. 

 Gorrie, by nearly similar means, has lately been made the 

 subject of a patent by Mr. James Rogers of Marlborough. 

 It is termed an instrument for determining the angles, from 

 the measure of the tangents of which the solid contents of 

 standing timber may be ascertained. On some future occasion 

 we shall give a description and figure of it; in the meantime, 

 such as are curious in dendrometers, will find Mr. R.'s de- 

 scribed in the Mechanics' Magazine, vol. vi. p. 295. It is cer- 

 tainly a most elegant instrument, but not more original and 

 ingenious than that of our correspondent Mr. Gorrie. — Cond. 



Art. IV. Scheme of a Succession of Crops for One Hundred 

 Acres of Arable Z,and in Picardy. By Thomas Blaikie, 

 Esq. C.M.H.S., &c. Landscape Gardener, Paris. 



Dear Sir, 

 I have received with pleasure your valuable work, the 

 Gardener's Magazine, which is well known here, and read 

 by M. Soulange Bodin, M. Cels, M. Boursault, and other 

 eminent cultivators and amateurs. I shall be most happy to 

 contribute to a work so truly devoted to our art, in every way 

 in my power ; and I now send you a farming scheme, made 

 for the French government soon after the Revolution, with a 



