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the numbers 3, 4, and 15, according as the observations are made on the coast in the midst of cultivated plantations, on the borders of mountain woods, or in the midst of those woods, There seems, however, to be some obscurity in an observation which the author is induced to make, namely, that the humidity of woods in the torrid zone extends far above the extremity of the scale. Now, as the hygrometer is usually graduated up to the point of complete humidity of the atmosphere, it can only be said that the moisture is precipitated in greater abundance than is necessary to bring the hygrometer to the highest degree.
We cannot venture to quote any more of these observations, or to explain the grounds of the doubts to which the conclusions drawn by the author give rise. But notwithstanding these doubts, we confess with pleasure that much information is to be found in the work. At the same time we must regret that the translator has not given to his version that great superiority over the original which it would have obtained had he subjected several of the author's statements, such as those relative to the comparative humidity of the Mark of Brandenburg and Holland, to critical investigation.
CHAP. IV.-Influence of Woods on Springs and Running
Water. That countries, especially mountainous countries, which are covered with woods, also abound more in waters than others, is a fact which may be asserted with little fear of contradiction.
CHAP. V.-Of the Influence of Woods on the Wind and on the
State of the Atmosphere with respect to Health. Though many remarks which occur in this chapter are just, we are much surprised at some of the assertions, and we think we do not err in considering them unfounded. Among these is the assertion that the impetuosity of the winds, where there are no woods to mitigate its violence, has rendered a great part of Great Britain barren. If the author's estimate, that the waste lands amount to of the whole surface of Great Britain be true, it does not follow that these lands are barren in consequence of a deficiency of trees. The heaths in the north of Germany, which are not all situated in places entirely destitute
of woods, shew clearly enough that circumstances, which accompany an effect, are not always those which produce it.
The comparison between that part of Tartary inhabited by the Calmucks and Lombardy, appears to be equally unfounded. Whoever in this instance, though the geographical latitude should be the same, expects to find the climate in both regions alike, and ascribes the dissimilarity of the climate to the want of trees in Tartary, must certainly have allowed many circumstances, which ought to have been taken into account, to pass unnoticed.
Chap. VI.-Influence of Woods on the Fertility of the Soil. We also meet 'with many remarkable observations and important conclusions in this chapter. But upon the whole, we think that this essay must be considered as a work which has not been reflected upon with sufficient deliberation. Nevertheless, it contains an abundant collection of curious facts; and though some of these facts are not well applied, and the accuracy of others remains to be proved, the book will, in the mean time be found an excellent contribution towards the explanation of the subjects of which it treats.
There are occasionally some obscurities in the reasoning; but whether these ought to be attributed to the author or the translator, we have not at present the means of determining.
Additional Remarks on the Stowage of Ships. By Commander
JOHN PEARSE, R. N. My former remarks were written with the intention of endeavouring to shew that we have no regular system for stowing our ships, and that an alteration in the distribution of the weights is necessary. Subsequent to their publication, I have seen an authentic calculation of the weight and pressure, according to the ordinary distribution in a modern 74-gun ship. This has induced me to publish these additional remarks, by which I shall be enabled to prove that the alterations I proposed would materially contribute to remedy the inequality of the weight and pressure represented in the calculation alluded to; and which is referred to in the following observations of Dr.
Young's, in his remarks on the employment of oblique riders. Philos. Trans. 1814.
" It is unnecessary to explain here the well-known inequality of the distribution of the weight and pressure, which causes almost all ships to have a tendency to arch or hog, that is, to become convex upwards, in the direction of their length. It is possible that there may be cases in which a strain of a very different nature is produced; but in ships of war this tendency appears to be universal.
“ It is, however, very different in degree in the different parts of a ship; and, of course, still more different according to the different modes of distribution of the ballast and stores, which may occur in different ships ; but, in ordinary cases, it will probably be found nearly such as is represented in the calculations subjoined in the note*, deduced from data, which have been obligingly furnished by an acute and experienced member of the Navy Board.”
By the above calculation, it will appear that there is an excess of weight at both extremities, and that in the adjoining sections the pressure greatly preponderates. Consequently, these forces are opposed to each other, and in a direction very prejudicial to the ship; as it is not only the evil of weight preponderating at the extremities, the power of which will be increased by the action of the ship, but from the formation of the body at those parts they can afford but a feeble resistance to so great a force.
Perhaps the following figures will best explain where the weights and pressure now preponderate, what particular weights may be supposed to cause an excess, and such as may be most conveniently and advantageously transferred. * “In a modern 74-gun ship, fitted for sea, the length being 176 feet,
the breadth 471, the the forces are thus distributed.
Aftermost 49 feet Weight 699
405 1098 409 461 3000
Difference 72 tons.
Figure the 1st represents the length of a 74-gun ship, divided into five sections, and the excess of weight or pressure in each.
Figure the 2nd also represents the length, divided into sections, and the positions of the masts, by which it will be seen that they are situated in those parts where the weights preponderate; and that they greatly contribute to it is a very natural conclusion.
In the foremost section there is, unavoidably, not only the weight of the foremast and its rigging, but the bowsprit and anchors also; the latter stowed at the extremity of the section, and the bowsprit projecting considerably beyond it; which, on the lever principle, assisted by the action of the ship and the excess of weight, and being situated in a part which from its formation affords but little resistance, and which is frequently left unsupported, must considerably augment the pitching motion, and contribute to the tendency to arch or hog.
In the aftermost section, the mizen-mast may be considered as contributing to the excess of weight; but it is not of such magnitude as the fore or mainmast; and its position is much more favourable for the ship than the foremast. The strain also on the after part is not so great as forward, as it is seldom left so entirely unsupported by the passing of a sea, and the sending motion is not so sudden or violent as the pitching.
In the extreme sections, and from the formation of those parts below the surface of the water, the upper works may also be considered as contributing to the excess of weight.
In the middle section, the mainmast, from its magnitude, may be considered as materially contributing to the excess of weight; and that, according to the ordinary distribution of the weights in the main hold, a large proportion of it may
supposed to fall in the vicinity of the mast. If this conclusion be admitted, it must appear prejudicial, and the more so, in con. sequence of the pressure preponderating so much at both extremities of the section. Among other weights concentrated about the mast is the shot locker, and which must considerably add to the unavoidable and too great weight of the mast alone acting on so small a space.
I shall now endeavour to explain, how far the alterations proposed in my former remarks would be likely to remedy the inequality of the distribution of the weight and pressure specified in the calculation.
In the foremost section No. 5, where there is at present an excess of weight, are placed the bower anchors, and the gunners', boatswains', and carpenters' sea-stores, which I proposed transferring; the anchors further aft, by removing the catheads to the fore-parts of the channels, which, although by the removal still situated in the same section, would considerably lessen the power of their weight on the ship in a sea; and the sea-stores to the after cock-pit, which will be found situated in section No. 2, where the pressure now preponderates. · In the after section No. 1, where there is also an excess of weight, the bread is stowed at the extremity; a part of which, together with beds, slops, marine clothing, &c., (at present stowed in the after cock-pit) I proposed should occupy present place of the sea-stores in section No. 5; which would reduce the excess of weight at present in the after extremity, and place less weight, more lively, and more speedily consumed than the sea-stores, in the place now occupied by them. Such arrangements would also be likely to contribute to a