Garden Libraries. 115 



'Art. V. Garden Libraries. 



MACKAY^ Clapton Nursery Library, July 20. — The Secretary is de- 

 sirous that we should acknowledge his obligation to Mr. Gorrie for a pre- 

 sent of his dendrometer, with the following instructions for its use, which 

 instructions may be considered as forming an appendix to Mr. Gorrie's 

 paper on the subject. (Vol. II. p. 8.) 



Mr. Gorrie's Dendrometer. — In constructing a dendrometer, it is neces- 

 sary to have the support and quadrant at exact right angles with the 

 table, in order to give the diameter on the principle of parallel lines. The 

 correctness of the sights in the quadrant may be proved by forming two 

 lines intersecting each other at right angles, placing the table on the direc- 

 tion of one of these lines, and moving the slider till the sights on the qua- 

 drant take the other ; if they are found incorrect they will be easily adjusted 

 by placing them so as to take the line. In placing the instrument for 

 measuring, the slider must be fifty feet from the tree ; and, should the 

 tree not be nearly perpendicular, it must be placed opposite that side where 

 the top of the bole neither comes near nor recedes from the point of 

 observation. In taking the diameter of slanting branches, the table must 

 be adjusted, by putting in or out the single leg, so as the side of the support 

 or quadrant will be in the same direction as the branch, the motion of the 

 slider will then bisect the branch at right across, and give the shortest, or 

 true diameter. 



In taking the length of slanting branches it will be necessary to take the 

 angle of elevation at the low end of the branch, then elevate the quadrant 

 to the apparent height, when it will be found that the sights do not point 

 to any part of the branch. The slider, or, if the distance is long, perhaps 

 the whole instrument, must be moved in a straight line till the quadrant 

 take the part of the branch where the angle is wished to be taken. The 

 degree of elevation will give the perpendicular height ; the space travelled 

 over by the slider will form the other angle of the right-angled triangle ; of 

 course the hypothenuse length is wanted as the length of the branch. 

 Suppose, by the table, the perpendicular height is found to be ten feet, and 

 the space travelled over two, then, by the forty-seventh proposition first 

 book of Euclid, the square of the hypothenuse of a right-angled triangle is 

 equal to the squares of both the other sides : Hence 10 X 10 = 100, and 

 and 2 X 2 = 4 -f 100= a/104 = 10 feetJ^; or 10 multiplied into itself 

 gives 100, and 2 multiplied into itself gives 4, and the sum of both squares 

 is 104 feet, the square root of which is 10 feet and -ig^ of a foot, or £ nearly, 

 and so on of any deviation more or less from the perpendicular. — A. Gorrie. 

 Annat Gardens, June, 1827. 



Toxteth Botanical and Horticultural Library. — At a meeting of some of 

 the inhabitants of the neighbourhood of Toxteth Park, held March, 1827, 

 it was resolved, — 



1st, That it is desirable to establish a library in Toxteth Park, for the pur- 

 pose of enabling those who desire it, to obtain information on the subjects 

 of botany, horticulture, and agriculture, at a moderate expense. 



2d, That such library be established, and denominated Toxteth Botanical 

 and Horticultural Library. 



A resolution was also passed, adopting rules for the regulation of the 

 Society. {Liverpool Mercury, June 1.) 



Our readers are requested to correct the name, and what is said of this 

 library, in Gard. Mag. vol. ii. p. 273., agreeably to the above information. 



Library of the Glasgow Horticultural Society. — We have received a 

 copy of the regulations of this library, as agreed on in February, 1827. As 

 far as we can judge, they seem very judicious. We are happy to learn that 



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