King's yards, is about fifteen years: and it is found that it will, upon an average, take about two loads of timber to build a ton of King's shipping which of courfe will make an annual confumption of 55.155 loads of timber. The Eaft India Company's fhipping, at the prefent time, (1792) contains 79,913 tons; to fupport which, will make an annual confumption of 8,300 to 10,000 loads. The tonnage of 'fhipping, in the merchants' fervice, transports, victualling, ordnance, customs, excife, and post-office, on the 30th September 1790, was no less than 1,480,990: to maintain which, will make an annual confumption of 113,074 loads; allowing the whole tonnage to be built over once in every twenty years, and allowing a load and a half of timber to build a ton. So that from this statement (which perhaps is near the truth) it appears, that it will require 177,379 loads of timber, to be supplied annually, to fupport the whole of the fhipping of this country, in its prefent ftate; which has increased one-third fince the acceffion of his Majefty in the year 1760. This consumption, together with what oak timber is used in house-building, mill-work, engines, canals, coopers' work, lighters, barges, boats, &c. from my own obfervations, and from all the information I have been able to collect, far exceeds the annual growth.

Having been conftantly employed in travelling over different parts of the kingdom, for thefe laft twenty years, to collect timber for the navy, I have of late, with grief, obferved a great diminution in the stock of growing timber, particularly of that which is applicable to naval uses; so much fo, that I do not believe that there is onetenth part of the quantity there was twenty years ago. If the timber in the kingdom continues to decrease in this rapid manner, and there is too much reafon to fuppofe it will, as the shipping continues to increase, and as there are no effectual means taken, either on the crown lands or private eftates, to keep up a fucceffion fufficient to anfwer the increased demand for it, the confequence must be obvious and alarming, and calls for fome effectual fteps to be immediately taken to leffen the confumption of timber, or to increase its growth, in order to fecure the fupply neceffary.

The great decrease of the stock of oak timber standing in the kingdom, be affured, my Lord, is not imaginary, but confirmed by all the Navy Purveyors in their Reports made feven years ago, from a general furvey taken by order of Government, as well as by the Commiffioners of the land revenue, in their eleventh report, who have taken infinite pains to afcertain the timbered state of the country.'

The propofed mode of preventing a calamity fo alarming to this country, in addition to what Mr. N. has formerly advanced refpecting the means of increasing the growth of oak timber, is to leffen the confumption of it in the navy; and in the moft defirable way imaginable: namely, by prolonging the duration of our hips of war, from fifteen or twenty to twenty-five or thirty years. This defideratum he proposes to effect, ift, By the proper feasoning and management of the timber, previously to its being converted for immediate ufe;

letting

letting it lie three years in the fap, before it is fided or hewn. 2dly, By building fhips of war in the dry, under sheds, as proposed in his former letter. 3dly, He propofes to let them ftand fome time in their frames before they are planked; and, when planked up, to leave as many of the holes for the treenails open, for at least twelve months, as can be left open with conveniency; alfo, in framing, to preferve a circulation of air between broad furfaces in contact, by means of grooves made across such surfaces; as well as to bore holes through the middles of large beams from end to end, in order to dry the timber quickly and effectually; and, after this is accomplished, to promote a circulation of air, under the well-founded idea that, after oak timber is made perfectly dry, and placed in a free open air, it will endure for ages.' 4thly, and laftly, He advises to keep fhips of war, when laid up in ordinary or otherwise, free from ftagnant and humid air, by means of the fire-ftoves which have lately been brought into ufe by order of the Navy Board.

With respect to iron knees, (which have lately been introduced into fome of the India fhips, and which the French have long been in the habit of ufing,-from neceffity, perhaps, rather than from choice,-) we are much pleased to find that Mr. N. is decidedly against them. Every man, who has made naval architecture any part of his ftudy, and who has paid any attention to the structure of fhips, will readily feel the force of his arguments in favour of timber knees.

As iron knees have been fuccefsfully introduced as fastenings, in the East India Company's fhips, by Mr. Snodgrafs, instead of oak, the Commiffioners of the land revenue, through him, have been induced to recommend them for faftening of our men of war; but as the adoption of this mode may be attended with very great and serious confequences to our navy, it certainly ought not to take place, in an extenfive manner, but upon the clearest proofs of its utility. From giving this fubject all the confideration in my power, and from attentively examining the ftate of the iron fastenings on board feveral Indiamen, I am perfectly satisfied that, however well iron knees are manufactured, they are much inferior to thofe of oak; and of this epinion are all the fhip-builders with whom I have converfed, except Mr. Snodgrass. As iron knees fpread a much less surface, they cannot keep the parts to which they are united fo fteady and firm as thofe of oak; nor is iron fo elaftic as wood, therefore more liable to give way and break; nor can iron knees be fo fecurely faftened as oak, being of a much fmaller fubftance; and the holes in the iron muft always be larger than the bolts by which they are fecured, and there. fore fubject to work loofe, which is exactly the reverfe in those of oak. On the whole, I am not able to perceive that the introduction of iron fastenings into our men of war, as proposed by Mr. Snodgrafs and others, can be attended with the least benefit, but may be productive

of much mischief. Though this mode of faftening may anfwer very well for the East India fhips, it does not follow that it would for our men of war: the topfides of Indiamen are much easier secured than, thofe of men of war, particularly of two and three decked fhips; there not being in the former that immenfe weight of guns, mafts, yards, topmafts, rigging, fails, anchors, &c. hanging to them, and of course not near the ftrain upon them, nor are they fubject to work fo much: yet our men of war, being fo fecure as they are with lodging and hanging knees, riders, breaft-hooks, tranform-knees, &c. of good English oak, are enabled to keep the most tempeftuous feas in the British Channel, and Bay of Bifcay, in the winter feafon, without giving out or complaining; and I believe it will be allowed, that more trying fituations than thefe, in general, are not to be found, for determining the ftrength of fhips. The unfortunate Royal George, at the time the met with that fhocking accident at Spirhead, was four or five and twenty years old, and had flood the feas in the British Channel, and Bay of Biscay, many winters, like a rock.'

To this reasoning Mr. Nichols adds facts, drawn from recent experience.

The Commiffioners of the Land Revenue having, in one of their Reports, thrown out an idea that the fcience of naval architecture has lately lain uncultivated in our dock-yards, Mr. Nichols takes up the charge in a fpirited manner; and, we think, fairly refutes it.

In fine, the naval department and the public at large appear to be much indebted to Mr. N.'s earneft and patriotic exertions, The Letter to the Commiffioners of the Navy relates to the method of what may be called the curing of timber for fhipbuilding. This letter fhould feem to have originated in other remarks of the Commiffioners of the Land Revenue, arifing from an answer of Mr. Snodgrafs, furveyor of the East India Company's fhipping; who, in reply to one of their queftions, faid that the moulding of timber, for the various purpofes of hip-building, may be done at or near the place where it grows, to great advantage." That an advantage arifes from this practice, fo far as it lightens the carriage, is as evident as that, in other refpects, it is abfurd in the extreme. To give timber its greatest degree of durability, it ought certainly to be cured in the fap: a fact well known to every poft and rail carpenter in the kingdom. Mr. Nichols obferves, with great ingenuity and truth, that by fiding or hewing timber presently after it is felled, and while full of juices or liquid fap, the annual coats of wood, of which trees are compofed, and which encompass them like hoops, and hold them together, are in part cut off, and the juices flying off very quick, frequently cause them to split or crack, and the cracks or fiffures receive the wet, which foon brings on rottennefs.' Not contented, however,

however, with found argument, our author has thought it right to collect, in perfon, the opinions of feveral eminent fhipbuilders; all of whom coincide with him. This laft was a labour which he could not have undertaken, but under a conviction of the great importance of the fubject; and it is from a fimilar impreffion that we have given an extra attention to this valuable little tract.

Mr. Nichols's obfervations on the nature of the Sap of Oak Trees are fuch as might be expected, from a man whose mind has long been employed on the fubject which he is difcuffing.

To his profeffional remarks, however, Mr. N. has thought fit to add a letter on a new Way of planting Acorns; and he clofes his pamphlet with a Lift of Books on Planting; a subject in which he appears to be uninformed. We regret that Mr. N. has thus unguardedly ftrayed beyond the line of his profeffion; within the pale of which he is perfectly at home; and where we shall be happy to find him, in future, whenever he may favour the public with farther remarks on ship-building, or the management of timber.

ART. XV. Cary's New Map of England and Wales, with Part of Scotland. 4to. Price 21. 28. in Sheets, or 21. 7s. with the Index included, in Boards. Cary. 1794.

THO

'HOUGH it is not our general practice to notice publications of this fort, yet, in the prefent inftance, we think that we shall do a service to our readers in pointing out to them the completion of a very useful work, which has been hitherto a defideratum, a good map of England. Mr. Cary, whose geographical merits have been made known by his county-maps, and other elegant and useful performances, has bestowed much labour and expence in accomplishing his design of giving a complete and accurate map of the whole country. In fuch an undertaking, the two things to be confidered are the materials and the execution. As to the first, the prefent map may be faid to be compofed from actual furvey; for, though such survey has not been made for the purpose by Mr. C., yet all the coun ties in the kingdom (except three,) having had maps of them published after actual furveys, the combination of these into a general map muft poffefs the fame advantage. With respect to the poft-roads, an important object in such a map, Mr. C. has been favoured with very liberal affiftance from the poft-office; inquiries having been officially circulated through all parts of the kingdom, and returns made of towns, ftages, and diftances, from the poft-masters of the respective districts. To the truth of this claim to fuperior accuracy we can bear witness, from a

view of fome of these official documents; and we think the circumftance equally creditable to the poft-mafters and to Mr. Cary. Navigable canals, another object now of great importance in a map of England, are laid down from the parliamentary lines of their courses.

The plan of the map is the fame that has been adopted in county-furveys when confifting of a large number of sheets. Their junction is fhewn by an index-map, fo divided into fquares as to correfpond with the number of plates in the large one, and the divifions are refpectively numbered alike. This work is comprized in 81 quarto pages, numbered in the manner above-mentioned, which may either be bound into a book for travelling, or pafted together to form one entire map. The fcale is one inch to five miles; the whole united will be 6 feet 7 inches high, by 6 feet wide. Proper difcriminations are made in the engraving and colouring, fo as to affift the eye: but we could have wifhed that the fize of letters in which the parifhes are engraven had not been quite fo large, as in fome populous counties they have a crowded look, which takes off both from the elegance and the diftin&tnefs. On the whole, however, the execution is very neat. The index of towns is copious, and effentially advantageous.

ART. XVI. A short Account of a new Method of Filtration by Afcent; with explanatory Sketches, on Six Plates. By James Peacock, Architect. 4to. 2s. Lackington.

THERE is confiderable ingenuity in Mr. Peacock's idea, but

accurate philofophy is wanting in fome paffages of this explanation of his defign. The effential parts of the apparatus here defcribed are two veffels communicating at their bottoms. The first answers to what is commonly called the head in machinery moved by water; the fecond contains frata of loofe particles of different degrees of fineness, through which the water, being forced up by the preffure of that in the firft veffel or rifing, according to a well-known hydroftatical law, to the fame level, leaves its impurities in the interftices of the particles between which it paffes. For fome particulars in the adaptation of this principle to ufe, the reader must be referred to the pamphlet and the plates. A more minute description we shall not, for an obvious reafon, attempt.

Now, by this contrivance, fuch matters only as are diffufed through the water, and not fuch as it holds diffolved, would be feparated and left behind. Mr. Peacock tried this with brine, and found the falt ftill remaining in the water, as any fmatterer in chemistry would have predicted.

The