It should be employed in different modes. must be allowed, at least, to have had the effect above explained that of relieving the heart and arteries from a great part of their exertion in propelling the blood, and may therefore have contributed to the cure by this means only. The different modes above mentioned are adapted from their nature to different degrees of bodily strength; and if there are cases, in which that which appears most eligible may not suit the situation or circumstances of the patient, it can not be difficult to contrive other means of giving motion, so as least to incommode, and yet to give the greatest relief. A very gentle and long continued, or even incessant motion, may suit some cases better than any more violent and occasional agitation; and in this way, Sea voyages. probably, it is, that sea voyages have sometimes been attended with remarkable advantage. Increase of trees of diffe VIII. Method of ascertaining the Value of Growing Timber Trees, at different and distant Periods of Time. By Mr. CHARLES WAISTELL, of High Holborn. (Concluded from p. 193.) Observations respecting Trees of different Lengths in the TREES that increase annually 12 inches in height and rent lengths of one in circumference, and have boles of different lengths, bole at diffe. these boles, if of the undermentioned lengths, increase after the rate of 5 per cent per annum at the ages and heights under-mentioned, and they measure as under, viz, rent ages, Whatever the lengths of the boles of trees increasing as above may be, the increase is 5 per cent per annum one year after their girt in the middle is 10 inches, but not longer. years But supposing that these trees have grown to 60 years of and at 60 age, and increased as above-mentioned, their girt and contents at that age would be as under, viz. This table shows, that the advantage to be gained by Boles of 32 pruning trees higher thau 32 feet is not an object worthy feet, of consideration, if the trees are to be cut down at the age of 60 years. And if it should be found, that, the higher a tree is 24 feet, pruned, the slower it swells in the bole, perhaps a 24 feet bole may measure as much at 60 years old as a 32 feet bole. If it increases half an inch in girt in the last 36 years more than the 32 feet bole increases in the same time, it will very nearly equal it in measure. A 32 feet bole with a top from 20 to 30 feet high, with and 40 feet. many large lateral branches, is certainly a much finer object than a forty feet bole with a top only twenty feet high, with a few and small lateral branches: and at sixty years old, the former will have had to increase in the last twenty-eight years only one quarter of an inch in girt, more than the latter, to exceed it in measure, to say nothing of the excess of timber in the larger top and branches. It must, however, be remarked, that at eighty years of age, the forty feet bole will exceed the thirty-two feet bole nearly six feet; and at one hundred years, thirteen feet, provided it swell equaily fast in thickness. But unless the trees be oak, fit for the use of the navy, for which an increased price can be bad, I imagine few gentlemen would now choose to let their trees stand to eighty years of age, when the increase of their boles will not be four per cent; still fewer would let them stand to one hundred, when the increase will not be three per cent per annum. Trees at 60 from 10 to 50 feet. Again, let it be supposed, that trees sixty years of age years of boles have increased annually, during their growth, fifteen inches in height, and one inch and a half in circumference, the girt and contents of their boles, if of the under-mentioned lengths, will be as under, viz. Contents Ft. in. p. Trees with 20 ft. boles will be 19 in. girt at 10 ft. high, 52 99 Do. do. 121 do. do. 61 0 5 67 6 0 Long boles may be more valuable in some ins tances. Elm and beech. Trees at 60 Taking it for granted, that the shorter boles will increase faster in thickness than the longer ones, it is reasonable to expect, that the forty feet bole will contain more timber than the fifty feet bole when they are both sixty years old; and if they are both sold at the same rate per foot, the forty feet bole must consequently be more valuable. If, however a higher price can be had for longer boles, this may compensate not only for their deficiency in measure at sixty years of age, but also for their standing beyond the period when they cease paying the common rate of interest for the money they are worth, which I suppose is frequently the case as to tall elm trecs, fit for keel pieces, and perhaps beech for ship planking. It is hence evident, that, where the soil is such as will enable trees to grow to a great height, it will be necessary, before we decide how high to prune them, to consider to what purposes the timber can be most advantageously appropriated. Whatever the lengths of the boles of trees increasing as above may be, their increase is five per cent per annum, one year after their girt in the middle is 15 inches, but not longer. Again, let it be supposed, that trees sixty years of age years of boles have increased annually, during their growth, eighteen inches in height, and two inches in circumference, the girt and contents of their boles, if of the undermentioned lengths, will be as under, viz. from 24 to 60. feet. Contents. Ft. in. p. Trees with 24 ft. boles will be 26 inches girt at 12 ft. high, 112 9 0 Here again we may suppose, that the forty-eight feet bole, by swelling faster than the sixty feet bole, may exceed it in measure at sixty years of age; and this it would do, were the girt increased only half an inch. And if the thirty-six feet bole was increased two inches in girt, it would exceed both the forty-eight and sixty feet boles. But trees of such swift growth are frequently cut down before they are sixty years old. At forty years of age the thirty-six feet bole, if it swell no faster than the forty-eight feet bole, will contain more timber if measured according to the present erroneous method. (The greater difpro- Present meportion there is between the two ends of a piece of timber, thod of measuring errothe more disadvantageously it measures, when the girt is taken in the middle.) I suppose that in timber of this swift growth, the longer boles are frequently not worth more per foot than the shorter boles; therefore, in this case, that length of bole should be fixed on, which is likely to measure most at the period when the trees are intended to be felled. 1 Whatever the lengths of the boles of trees increasing as above may be, their increase is five per cent per annum, one year after their girt in the middle is 20 inches, but not longer. It appears from the last observations and calculations, that the annual increase in the boles of trees by their growth ceases to be equal to five per cent per annum some time between forty-six and sixty years of age, according as the boles are shorter or longer. neous. But it being generally allowed, that oak trees, of a size Size of oaks fit for the navy, require to grow from eighty to one hundred for the navy and fifty years, according to the quality of the soil; and it is so stated in the eleventh report of the commissioners appointed to inquire into the state and condition of the woods, forests, and land revenues of the crown; I have therefore been calculating tables, showing what the propor- requires a very tionably advanced prices should be, at different periods, up high price. to one hundred and fifty years, to pay the proprietors for letting their trees stand to those periods. These prices, especially at the later periods, very greatly exceed any that have ever been given. It certainly has been much the interest Loss on their standing 120 years. Instances of interest of the growers of oak timber to fell it at about sixty years of age, even if they replant the same ground. To let it stand to one hundred and twenty years of age, and sell it at the present prices, their loss would exceed double the whole value of the timber at sixty years of age. Nothing short of a sufficient price will long command a sufficient supply. Owing to too low prices the quantity of large timber on private estates has long been rapidly decreasing; and it will be too late to commence offering reasonable prices for it, when it is all gone, and no oaks left of greater growth than sixty years. To have to wait their growing the second sixty years may bring upon us evils exceeding all calculation. Valuations made in October, 1807, of several Plantations in The valuations were made of the trees growing within profit on plan the space of a chain square, being the tenth part of an acre, tations of oak, of the medium growth of each plantation. In the plantation by the mill wall there are now growing within twenty-two yards square, as under, viz. The above is part of about four acres planted in 1775, on a strong loamy soil, worth about 20s. an acre. One pound per ann. forborn 32 years, and im- amount to £. s. d. But the value of the timber is more than three times this amount. The ground was prepared for planting by ploughing. On |