The most obvious plan is an inclined plane; the waggon full of ore descending, to draw up the ascending empty one.

Fir timber is to be obtained at a moderate rate; would not, there fore, a tram road of balks answer equally well with an iron one?

If so, would a different kind of waggon from that usually employed be necessary? Must the wheels be broader? or would trucks, with out wheels, answer better than waggons? Would a half-inch chain let down three tons of ore? would be the size of a rope to correspond? And how long would each, probably, last, supposing 3000 tons were the quantity to be conveyed annually?

What

What kind of machinery would be necessary in order to regulate the velocity of the descending waggon? Would a double chain or rope be necessary?

After the ore is shipped it is to be re-landed, in order to be crushed; the distance from the landing place to the crushing-mill is 50 yards; the angle is 15 deg. It is proposed to employ the water-wheel of the crushing-mill to draw up the waggon full of ore.

What weight would a half-inch chain draw up? And as the friction caused by the loaded waggon ascending would be much greater than in conveying the ore from the mine to the water's edge, where the loaded waggon descends, would it be necessary here to have an iron tram road? or would a wooden one also answer here?

SOCIETY FOR THE DIFFUSION OF

USEFUL KNOWLEDGE.

Sir, I am entirely of your opinion, that the discussion in reference to this new Society has been carried quite far enough to answer all the purposes of fair inquiry. And as I have no doubt that the majority of your readers perceive that "Mentor" leaves the citadel of my main and original statements untouched, as well as most of my subsequent reasonings, while he diverts himself with some skirmishing at the least

13

important of the outworks, I may very quietly leave much that he advances in his last letter without reply. Regarding, then, as I trust I now may, my first position with respect to the Society as established, I shall merely notice a few particulars, in which "Mentor" either calls in question my assertions, or seems to intimate a want of consistency and fairness in the course I have pursued.

The charge of inconsistency, however, as well as that of unfairness, may at once be disposed of; for they hang merely upon this, that I have advanced statements, arguments, and opinions, in my later letters, that I did not specify in my first; as if the essence of discussion consisted, in reiterating the same things, and scrupulously avoiding the mention of any fact, or the developement of any sentiment, in a reply, or a series of replies, but what had been adduced in the outset. Very amusing, truly! and very convincing!" You said so"-"but I say so," from the beginning to the end of the chapter.

Thus, I have praised some of the Society's pamphlets, and I have found fault with others. But, since this does not all occur in one letter, "Mentor" very gravely informs us that this" one circumstance struck him as singular." In my latter letters, too, I speak of the influence of the Society, which "Mentor" regards as very unfair; for in my first letter he does not find the word influence. It may be so. But, in my first letter, I said that "the direct and constant tendency of the Society was to check the spirit of enterprise," &c.; and how, when this is denied, or attempted to be denied, I could prove the tendency to produce the injurious result, without showing that its influences inevitably involved it, it is not for me to say. Perhaps, when "Mentor" publishes the Society's Treatise of LOGIC, upon which, I presume, he is engaged, he may favour us with a few corollaries, in which all this may be made very obvious.

My assertion was, that in two years the Society had delivered to

its members forty or forty-one pamphlets; and the fact, I believe, is, that the Society started in January, 1827, and published its fortieth Number on the 14th of December, 1828. It is truly munificent to present me with the benefit of a correct statement under the denomination of an error. Let me entreat that, for the rejection of it, I may not be classed with the "factious," among whom it would seem your unfortunate correspondent "Libra" has enrolled himself.

Passing by "Mentor's" reference to the "Library for the People," which I neither mentioned, nor had in my thoughts, I proceed to his attempt to rebut my charge of plagiarism, in the first Number of the "British Almanac." In truth, I feel that such a charge is too serious to be brought forward, without having fully ascertained its correctness. I repeat the assertion, that the plagiarism was universal, as to all the essentials of an Almanac; and that the theft of the Tide-table, of the responsibility for which "Mentor" endeavours to free his friends, by a piece of ridiculous, hypothetical reasoning, was only one portion of the general piracy. The manufacturer of the "British Almanac" could not have computed from the Tables, &c. used in the computation of " White's Ephemeris;" for this plain reason, that he could not possibly have them to compute from.

During my last Christmas holidays, being in London, I ascer tained, by means of my bookseller, who is an active member of the Stationers' Company, the real fact as to this matter. He assured me, that the Editor of " White's Ephemeris" computes the times of high water at London Bridge by precepts and Tables of which no person but himself has a copy; that, to render these as correct as possible, and to incorporate in them the effects of new bridges, and other erections, he for years paid periodical visits to the platform of the London Bridge

* Who will, doubtless, come forward, and contradict this statement, if it is incorrect.

Water Works, and had regular ac cess to the register of the tides kept in the Office of these Works; that since their removal, he has had the circumstances of the tide examined and recorded at the New London Bridge, even up to the autumn of last year; and that this incessant watchfulness gives an obvious advantage to the rules thus fitted to circumstances as they arise, which none but rules acquired 'and modified with equal care can possess. What, then, becomes of "Mentor's" sublime illustration of setting them to do a division sum?" Perhaps he means the division of nothing by a thousand; for in that case, the amount of the quotient, or that of the remainder, equally mea. sures the value of his argument.

"Mentor" is equally successful in rebutting the charge of misstatement of the general character of the Stationers' Company's Almanacs. He tells us he "is perfectly convinced, that every statement in the Preface is in accordance with the strictest truth." Is it, then, "" con. "sistent with the strictest truth," that "two-thirds of these publica. tions contain a large portion of" astrological "matter, and thus keep alive a spirit of ignorance," &c.? From the announcement on the wrapper of the "Englishman's Almanac," it appears that the Company publish twenty-four Alma nacs, three of which only contain astrological predictions. "Mentor," then, has made the admirable discovery, that three are two-thirds of twenty-four; a discovery which I suppose is derived from the dexterous management of his "division sum.'

Is it, again," consistent with the strictest truth," that "none of the Almanacs of the Continental States contain any misleading matters of this (astrological) nature ?" If so, what has become of the "Astrologue Normand,"-the Francis Moore of Normandy, of which more than 100,000 are sold annually, and a great portion of them even in Paris? With such notions of the strictest truth, would it not be adviseable for the Society to employ

their advocate upon a Treatise of Moral Philosophy? It might exhibit some new discoveries in ethics, as valuable as the arithmetical discovery to which I have just adverted.

"As to the charge concerning hush-money," says "Mentor," "such an accusation should be substantiated, or not made at all." At my distance from the metropolis, and enjoying no intercourse with those who know the fact, your correspondent's demand upon me here is rather hard. I will try, however, to oblige him, though 1 certainly had no wish to be thus particular. The pamphlet which was in the unhappy predicament to which I alluded, was the "Life of Sir Christopher Wren;" and the sum paid was fifty guineas. Neither my allusion to the fact, nor my reasoning upon it, implied any censure of the Committee. "Mentor" himself has not a higher opinion of their honour and integrity than I have. My inference from the fact rested upon the influence of the body, not upon any individual act; and that inference remains unrefuted. Besides which, what is the value of the superintendence of the members of the Committee, that they did not detect the plagiarism before publication?

66 Mentor," "whose intellectual optics are peculiar to himself, has de tected some very inaccurate reasoning in my account of the successive revisions and authors of the Treatises on Mechanics. It seems, there is 66 no author of the present day, who has the smallest regard for his reputation," but would be anxious to subject his work to a similar process —that is, have it altogether rejected, and another man finish it for him. Of course, r Mentor" is quite convinced, that the Treatises on Mechanics, for example, by Wood, Marrat, Gregory, Bridge, Whewell, were thus prepared to meet the public eye. Now, it would be a curious instance of literary inquiry, and, I conjecture, in a totally new department, to ascertain, with regard to any one of these (suppose the valuable Treatises of Mr. Whe

15

well), who began it-who revised it-who printed it-who re-revised it-who reprinted it-who was the second author-who was the third author, and, finally, where, in the extraordinary list, Mr. Whewell's name should be placed?

"Mentor" is seized with another fit of confidence with reference to the Society's Treatises on Hydrostatics-" of course, the expurgated edition." I really have no desire to deprive that pamphlet of any merit which it may possess; yet I think it is one of those which is correctly characterized by saying, that while it is too scientific for the prac tical man, it is too popular, and merely descriptive, for the man of science. Vince's little book (of which, however, I am by no means an admirer) is very far preferable for a student who wishes to go beyond a mere dogmatical and popular essay. Nor would I hesitate to recommend Bland's book as infinitely preferable to Francœur's, notwithstanding the opinion of "Mentor,' and the frequent use of the latter at Cambridge, in consequence of the ridiculous fashion which prevails there of preferring French to English mathematical books, whatever may be their relative merits.

By the way, I shall in some measure repay your readers for their patient perusal of my letters, by recommending to their notice "Marrat's Elements of Natural Philosophy," published at Liverpool about three years ago, and sold by Longman and Co. In an octavo volume of 214 pages, price 7s. 6d., the subjects of Mechanics, Hydrostatics, Hydraulics, and Pneumatics, are far better handled for real students than in the Society's Treatises. The method of investigation is correct, scientific, and uniform (an advantage to which the Society's Treatises make no pretensions); the examples are numerous and well chosen; and many subordinate and connected topics, altogether neglected in the pamphlets, are therein introduced and adequately treated. It is one of the evils resulting from the Society, that it has been the occasion of thrusting this truly in

structive volume, notwithstanding its cheapness, entirely out of the market.

Lastly, let me invite the attention of your readers to one fact which would alone be decisive in proving that the rivalry of the Society to booksellers and authors unconnected with them, bears no analogy to the general operations of trade, or the honest and persevering efforts of one bookseller or author to sell more books than another. The Society is positively certain of the sale of 1000 copies, at least, of each pamphlet, on the moment of publication, before the reading men to whom I alluded in my second letter, begin to make their purchases. They are sure, that is to say, of a remunerating price, from the mere constitution of the Society, before even its influence (I mean the influence of its reputation) comes into play upon the public generally; and that whether the pamphlet be good, bad, or indifferent. Now, what bookseller is certain of the sale of 1000 copies, or of 750, or of 500, or of even 250, of every successive publiIcation that issues from his house? Would not such a certainty change the entire nature of the bookselling trade? Would it not deprive it of an essential of trade, as subject to loss, as well as gain? Would it not deluge the world with trash, and ruin the character of our literature?

Let us hear no more, then, of the similarity of circumstances with which the booksellers and the Society do enter, or might enter, the market. There is no similarity; and no modification of the Society's measures can now produce any. So that its advocates must relinquish that mode of defence, and either abandon the principles of political economy which its leading members are known to hold, or show that they are not, as I still affirm, utterly repugnant to the measures pursued by the Society from its very commencement.

I am, &c.

A COUNTRY SCHOOLMASTER. -e, Essex,

Feb. 9, 1829.

MISCELLANEOUS NOTICES.

Dip of the Needle.-A paper by Captain Sabine was read to the Royal Society on the 8th Jan.last, on the dip of the magnetic needle (the angle which it makes with the horizon) in August 1828. In 1576, Norman, the inventor of the dipping needle (who was a humble maker of compasses at Ratcliffe), found the dip in London to be 71 deg. 50 m. According to observations made at a later period, and recorded in the " Philosophical Transactions," the medium quantity ap. peared to be 72 deg. The experiments made in August 1828, and detailed in Captain Sabine's paper, show that this quantity is diminished to 69 deg. 47 m. N. Captain S. states, that for the century preceding 1821, there appears, from the most authentic registries, to have been an annual decrease in the dip at London, of rather more than 3 m.,-a result which nearly agrees with similar observations made at Paris.

Anti-corrosive Wood.-The hemlock tree has been found to possess the remarkable property of preserving iron inserted in it from corrosion even when under water.

Sallpetre from Beet Root.-M. Henri Braconnot has ascertained that the stem and leaves of the common beet, when dried and burned, yield ashes so rich in alkali, that it melts easily by heat, and surpasses many of the commercial varieties of potash.

The odour of Musk, Tobacco, &c.-which dis appears almost entirely when these articles become perfectly dry, may be restored by moistening them with a weak solution of ammonia.

The Earth.-Is it likely that Providence, which has assigned the earth as the residence of man, of animated nature, and for the growth of vegetation, should have merely adapted the external crust to the purpose, filling all the internal recesses of the globe with inert and ponderous matter, inaccessible to man or other creatures? It appears to us more consonant, therefore, with what we know of the economy and the harmony of nature, to believe that the earth is not solid to the centre, as is generally supposed, but that in its vast recesses there is ample scope for the free enjoy. ment of animal life; nor is there anything extravagant in the supposition that the interior cavity of the earth may be as well illuminated as the exterior surface. The hand that could light up the torch of the cold glow-worm, could render the subterranean vault visible at will.-Professor Leslie's Theory

INTERIM NOTICES.

We admit "Libra's" claim of right to a few words in reply to the aspersions of "Mentor," but cannot spare room for them this week.

Communications received from Chelmeriensis Mr. Utting-G. S.-O. C. F.-P. M. W.Mr. Oliff-A-E. S. 'L.-R. C., Jun.-Zero-T -C. H. R.-E. F. Draper-Mr. Ford.

The Supplement to Vol. X., containing Titles, Preface, Index, &c., with a Portrait of the Right Hon. Robert Peel, will be ready for delivery on the 1st of March.

Communications (post paid) to be addressed to the Editor, at the Publishers, KNIGHT and LACEY, 55, Paternoster Row, London. Printed by G. Duckworth, 76, Fleet-street,