produce, and yet how many living witnesses could be found who have, for more than three score years and ten, drank this (slowly) poisonous compound! I defy "B." to produce a single case of loss of life through drinking impure water; and further, I defy him to produce a single case of the slightest indisposition produced by water as supplied by any of the public companies!

If the impurities of the water came with the supply of that element, all houses on one service would be alike as regarded the state of their cisterns: while the fact is, that a constant variation is observed, regulated by varying circum

stances.

The remarks of "B." have almost driven me into the position of an apologist for the Water Companies--a task as uncongenial to my feelings, as it is beyond my powers. It is very natural that "B." should treat my letter quite as "a matter of business," but he is most completely mistaken. I have no wish to "offer my services," for a consideration, "to wealthy corporations at the hour of their trial "if such trial be approaching. I decline any such employment. It is now twenty years since I commenced as a humble, though zealous, and to some extent a successful, labourer in the task of reforming the water supply at fires-labouring at my own personal and pecuniary cost to benefit my fellow-men-or, as B." would have it, to serve the wealthiest of corporations -and this without expecting, seeking, or receiving the smallest fee or reward. No great marvel, then, that during this period, and so employed, I should have had a more practical insight into the whole matter of water supply than casual or interested observers.

Having laboured thus far pro bono publico, I beg leave to say, that neither my age nor circumstances are yet such as to lead me to adopt that which Byron describes as a 66 good old gentlemanly vice."

Wishing "B." every possible success in the business to which he has lent himself, and expressing my determination to give him a push behind, on the manifestation of any "stop short movement,"

I remain, Sir, yours respectfully,
WM. BADDEley.

29, Alfred-street, Islington,
Sept. 19, 1842,

THE LATE CAPT. A. VIVIAN.

(From the Mining Journal.)

When such a man as the late much-respected and talented individual, Captain Andrew Vivian, of Camborne, passes from among us, "to that country from whose bourne no traveller returns," his death deserves more than a passing notice at our hands. Descended from respectable parents, he received an education fitting him for the station in life which he was destined to fill, and, from his thorough acquaintance with mineralogy and mining operations, the neighbourhood in which he lived derived immeasurable benefit. The renewal of the works of the abandoned Dolcoath run of copper mines, and North Roskear, which subsequently proved eminently successful, whereby a dense population has been kept throughout a series of years in constant employment, were the result of his exertions, as were also those of Crenver Oatfield and Wheal Abraham, Binner Downs, and Wheal Treasury, with similar results. In testimony of his invaluable services, the Dolcoath adventurers, through the late right hon. Lord de Dunstanville, in the year 1806, presented him with a handsome piece of plate, with an appropriate inscription. Being one of the principal mine agents of Cornwall, he was repeatedly required to give evidence before the House of Commons touching mining affairs, and, as such, mainly contributed to procure the allowance of debenture upon the Norway timber used and consumed in the mines. He was well grounded in the science of mathematics, and, as an engineer, ranked with the first of his day. To him, in conjunction with Trevethick, is the world indebted for the construction of that gigantic and wonder-working machine, the locomotive-engine-a distinction of which Cornwall may justly boast. The author of this brief sketch well remembers an evening in the year 1801, when Captain Vivian first made his experiments upon the common roads. Its novelty attracted together a great concourse of people; the leviathan machine proceeded through the town, treading the streets in the power of her might. Her deep breathings, as she ejected the steam at every stroke, and the fire and smoke escaping from her, gave a wild romantic effect to the whole scene, and led a quaint old lady to ask-What will they attempt next? at the same time exclaiming, she could compare it to nothing less than a walking devil. For this invention, in February, 1802, he obtained a patent, and shortly after sold the patent right to Messrs. Boulton and Watt, who also presented him with a superb piece of plate on the occasion. The extraordinary energies of the late Captain Vivian's character and

faculties and powers of mind were strikingly illustrated by the fact, that at one period of his life, besides that he was an extensive banker, which business he conducted with great credit to himself, he carried on a large business as a maltster, tallow-chandler, and general merchant-superintended the management of eighteen mines-was the confidential agent of several considerable landed proprietors and, withal, was no inconsiderable experimental farmer. He was sincerely public-spirited, and ever found ready to join and promote every undertaking in his opinion calculated to conduce to public good, and posterity will acknowledge to him a debt of gratitude. Possessed of a great fund of wit and humour, he had the talent of relating anecdotes in a very amusing and agreeable manner, which, united to a remarkably cheerful and frank disposition, rendered him a most desirable companion. In acts of benevolence "large was his bounty, and his soul

sincere." As a kind and indulgent parent he was never surpassed, and the fatherless never failed to find in him a friend and protector, nor did he ever permit deserving objects of distress to ask relief in vain. Early in life he became the confidential agent of the families of Trelowarren and Pendarves, and the estimation in which they held him is marked by the circumstance, that, although increasing age and infirmities had for several years incapacitated him for the duties of his office, the present baronet, Sir Richard Rawlinson Vyvyan, and Mr. Pendarves, M.P. generously continued his salaries to the last. He was for some years a consistent member of the Wesleyan Methodist Society, and died in the full assurance of a blessed immortality, on the 5th day of September, 1842, in the eighty-third year of his age. His memory will long be cherished and revered by his family, and a numerous circle of friends and acquaintances.

BY EDMUND

Fig. 2.

the minute expiring, the line is seized and hauled in to the first series of knots, which, should there be 8, signifies that the vessel is going eight knots or miles per hour.

By the contrivance represented in the accompanying sketches, the velocity may at all times, without any one's aid,

be known. To the present float, fig, 1, which has its convex border loaded with lead to keep it upright, attach a cord of a definite length, say 20 or 30 yards, and connect its other end to a Salter's spring balance, as shown in fig. 2. Now as the resistance of the float increases with the velocity of the vessel,

this balance, by a few carefully conducted experiments, may be divided into miles in lieu of pounds. This being done, it is evident that if the float be permitted to continue overboard, the spring balance, or indicator, which may be fixed in some conspicuous place, will at all times denote the speed of the ship. Manchester, Sept. 7, 1842.

THE CRANK QUESTION.

Sir, I am glad to perceive by your correspondent "M's." last letter, that he is now satisfied to allow, that his loss is but a "mechanical disadvantage," as I presume it augurs a speedy conclusion to our controversy. Your correspondent seems inclined to chuckle at what he considers a concession on my part; but he must have a very short memory if he forgets that this was the very position I took up, in my first letter on the subject; and that then he disclaimed such an idea with indignation; I brought it forward knowing that it was the rock many a practician had split upon, supposing that where a mechanical disadvantage existed, it must cause a loss of power. I shall just quote the passage (Vol. 34, page 389.) "When in any system, a power acts at a mechanical disadvantage, being by a lesser power held in equilibrio, so that no motion can ensue, it may be argued, that there is a loss of power suffered by the greater. This use of the expression, loss of power, which is not unfrequent, is, however, both highly objectionable and incorrect ;-for if we say there is a loss of power in the lever, when by means of it, a greater power is held in equilibrio by a lesser, we must also say that there is a loss of power in the crank, when statically considered in a state of equilibrio. When, however, motion takes place, we immediately see how the matter stands; the doctrine of virtual velocities shows us that there is no loss of force whatever when the system is in motion, and therefore that there could have been none when it was at rest.' I also used the following expression, "if M.' should still suppose that when there is a mechanical disadvantage, there must be also a loss of force, he may," &c.

Your correspondent, however, at that time would not at all give in to this idea, stating clearly in his reply, that he did not contend that when a lesser power held a greater in equilibrio and that no motion ensues, that there must be a loss of power-nothing could be farther from his meaning."

Thus, then, Sir, my original supposition

VOL. XXXVII.

has turned out to be quite correct; but I do not on that account want to claim any victory in the matter; it was not for that purpose I commenced the controversy: and moreover, I am quite willing to permit your correspondent to be considered as victor, under the law which he tells us obtains among a certain order of quadrupeds.

66

me

You will think perhaps, Sir, that I might as well conclude here, the matter being comparatively settled; however, as I hope this will be my last letter, I dare say you will bear with me while I make a few further remarks on your correspondent's communication. I cannot but perceive that in several places he tries to make it appear that I admit that there is a "mechanical deficiency of effect" in the crank, in admitting a chanical disadvantage.' I suppose he would contend that there was no difference; but, if there is not, why bring in a new expression at all? And if there is, (as there evidently is a great difference,) it is only another proof that arguments alone are not sufficient to support his cause. I used the expression "mechanical disadvantage," as I thought its meaning could not be mistaken, from its being so often used in works on mechanics, in treating of the mechanical powers, lever, pulley, &c., where nobody ever dreamed of there being a loss of force; so that your correspondent is greatly mistaken in supposing that I am ready to join him, in condemning those gentlemen, who he says, consider that any person contending for a loss of power in the crank, must be "unacquainted with the first principles of mechanics :" far from agreeing with him in this, I consider his own arguments strong confirmations of the fact.

In a former letter he had accused me of cavilling with him about friction. I denied the charge in toto, and now he says that indeed it is very true that I did not mention friction, but that it is equally true that he did! A pretty excuse this for an erroneous accusation! The reason he gives for my not bringing forward friction is truly absurd, viz. that indeed I "was too cautious to commit" myself; how I was to commit myself by mentioning it does not appear, and does pass my comprehension.

It seems now that it is friction which is to be blamed and not the crank; for he tells us that all his arguments are founded upon it, and, (what he never said before, though he thinks he did,) "that the crank, considered in the abstract, and without reference to friction, might, for all the purposes of his experiments and the line of argument made use of, be supposed incapable of losing power." This is a great admission, and goes far to clear up the character of the

X

men on board the Blackwall, who stated that they saw the Queen go down the river, and from the paddle-box of the Blackwall watched her progress; that the Blackwall, as near as could be ascertained by judgment measure, gained one mile, and in time, four minutes; but that none of them ever saw the Queen stop.

I now come to the "more fair trial," (in "L. P.'s" view,) on the 12th August, to which it would appear the feat of Samson carrying off the gates of Gaza is but a puny effort.

"When Greek meets Greek then comes the tug of war;" and so it was. The Queen drew up alongside, bent on mischief, and started along with the Blackwall, the Blackwall carrying only feather weight (30 or 40 passengers), by "L. P.'s" measure, and the Queen 5 tons superfluous coals. The Queen, nevertheless, went round the head of the Blackwall in Long Reach. Happy for the Blackwall it was Long Reach; to have been so beaten in a short one would have damned her for ever. It would have been candid if "L. P." had informed the public, or rather, the scientific world, as he prefers, (which, by-the-by, I think is a stave higher up the ladder, than the common term public,) how this going round ahead in Long Reach was effected. As he has not done so, I will inform your readers. The Queen passed the Blackwall whilst making a stoppage; and the very moment she was again being put in motion, the Queen, as if convinced of being defeated, had the run been continued, took a course across the bows of the Blackwall, which had again to ease her engine to avoid doing damage to the Queen, which then rounded, and again proceeded down Long Reach.

In claiming victories for his Queen over the Railway and the Blackwall upon the grounds he has set forth, "L. P." evinces but little acquaintance with river practice, and the effect of varied cargoes. It is well known that even thirty or forty passengers in various positions upon a slight river boat will materially affect her trim. Neither is a general repair at the beginning of a season, to such hardworked boats as these, any guarantee for their being in condition, or at the top of their usual speed, six months after. The number of trips made, and passengers carried between Blackwall and Gravesend, with the continual easing, stopping, going astern, and again a-head, will readily explain to any one conversant with such practice, how utterly impossible it is that during their season, and under such circumstances, they can be found in fit and fair condition to run with new boats, prepared and brought out for "state occasions." Though "L. P." may satisfy himself that

small-leaved laurel gathered from results like those he has cited are valuable, the public at least can justly appreciate them.

I have now only one other remark to offer, for with the circumstances of the Queen's defeat by the Isle of Thanet, I am not acquainted; and it is this-that as no opportunity of a fair trial, under similar circumstances, has yet occurred, I would suggest that at the commencement of the next season, after the Railway and Blackwall will probably have been renovated, and be in a good average condition, the Queen should then take a run with them from Blackwall to the Nore and back, which, presuming they are freighted equally and managed with equal skill, would test their comparative steaming powers beyond all possibility of dispute. Or let them run day by day alike for a week or two, and then compare notes.

Having been guided in the statements I have made by the strictest regard to truth and fair play, and being not aware that any other construction can be placed upon them, I quit the subject with my best thanks to you for the kind and prompt attention you have given at all times to my communications, and for permitting them to find a place in your valuable, highly esteemed, and useful publication.

Believe me to remain, Sir,
Your obliged and obedient servant,
VERITAS.

September 15, 1842.

INSTITUTION OF CIVIL ENGINEERS.
June 7, 1842.

"An Account of the Alterations to Tullow Bridge." By Charles Forth.

The old Bridge at Tullow, over the river Slaney, was very dangerous from its steepness, its narrow roadway, (only 18 feet wide,) and the awkward approaches to it; alterations were therefore determined upon, for which the author submitted a plan, and also superintended the execution of it. The floods forbade any diminution of the waterway, and it would have been inconvenient to have raised the approaches on the low banks on either side; flat arches of the subjoined proportions were therefore decided upon.

The inclination of the roadway was thus reduced from one in seven to one in forty, while at the same time, by adding to the abutments on the up-stream side, the width of the roadway was increased from 17 feet to 28 feet, and, by completing a portion at a time, the thoroughfare over the bridge was not at any time stopped. For the sake of economy, the work was done in undressed rubble granite, with an ashlar face, taking