=Measuring the Height of Trees.=—There are several methods of ascertaining the heights of trees, but the two following are, perhaps, the most simple, and the appliances necessary quite inexpensive:— No 1.—Take three laths, such as bricklayers use for tiling, and nail them in the shape of the frame shown; _a a_ must be of equal length; _a_ and _b_ being placed on the ground, the eye must follow up the larger lath _d d_ until it is in a line with _e_, the top of the tree or object you wish to measure. The frame must be placed as level with the bottom of the tree as possible. Should the ground be very uneven you must give and take accordingly. It will be seen that _b_ to _c_ is the same length as _c_ to _e_, and this gives the height of the tree. No 2.—Suspend the triangle between the thumb and forefinger of the left hand, knuckles down, upon the point _a a_, allowing it to swing freely. The edge _b c_ will then fall perpendicularly, and _c d_ will be horizontal. The remaining edge _d b_ will then lie at an angle of 45 to the horizon. On this edge are two sights, _e_ and _f_. Look through _e_ until _f_ is aligned with the tree-top, advancing or retiring till the sights point exactly to it. Then, if the observer’s feet are level with the tree root, the height of the tree is the distance from his feet to the root, plus the height of the eye from the ground. The dendrometer is perhaps the most useful instrument for taking the height of a tree and can be procured from some of our nurserymen. CHAPTER XXXI BLASTING AND BURNING TREE ROOTS [Illustration: BLASTING AND BURNING TREE ROOTS] Blasting by gunpowder or dynamite is not only the most expeditious but also the cheapest method of clearing away tree stumps and large logs. In preparing to blast a stump, great care must be exercised to bore the hole in the right place and not to use too much explosive. For blasting powder the hole should be 1½ in. in diameter, and should penetrate to the centre of the stump. It must not be too low down, lest the bottom should blow out and the force be expended in shattering the ground instead of the stump or log. In selecting the spot to bore for the powder, choose the hardest part of the root and ensure an equal thickness of wood all round, and even splitting of the log will be the result. The following is a good way of putting in the powder:—For large stumps of from 2 ft. to 4 ft. in diameter about 3½ in. depth of coarse blasting powder should be inserted in a hole 1½ in. in diameter. The end of the fuse should be put into the centre of the powder, and left protruding for 15 in. outside the hole, which is filled with dry sand, consolidated, or packed around the fuse by means of a coarse iron wire. The outside end of the fuse should be teased out and lighted with a match, and as it will require over a minute for the fire to reach the powder, time is given for the operator to find a place of safety.