1

* *

withdrawn from business, and am now a very old man, so that I
can be of no use to your friend as an associate or patron.
I hope yourself and your friend will excuse my incredulity, but I
have very long been satisfied that there can be no such thing on
earth as a perpetual motion, generated in the machine itself,
without the expenditure of some external power or cause of
motion. All the known elements have, as I believe, been already
applied to machinery, and you do not infer that your friend has
discovered any new one. It is possible that he may be deceiving
himself, and I would therefore recommend to him, before he pro-
ceeds further, to make a working model of his machine, on as
large a scale as he can, and from it to calculate the power and
the probable expense of exciting it, and not to take any other
steps in the business until he is satisfied he is in no mistake. * *

"I should have very great reluctance to be made the depositary of the secret of any invention which is not secured by patent. Should the invention not meet my approbation, it would lay me under the disagreeable necessity of speaking my sentiments upon it, which might be construed as dictated by interested motives ; or, if the secret got abroad by other means, I might be blamed for it. Yet, on the other hand, the inventor might be benefited by my advice, the fruit of fifty years' experience in mechanics. On the whole, I wish to decline the confidence; but if I can give any useful advice, without a full confidence, I shall be glad to be of use to any ingenious man. If your friend will answer me by letter the following questions, it may save him the coming here, should he, after what I have said, think that proper. Is there no expenditure of any power or agent extraneous to the machine itself? and, if so, what may be the expense in money to enable the machine to raise 30,000 cubic feet of water 1 foot high? Is that extraneous agent any of the known powers or elements which have been employed to raise water, or give motion to machines, such as fire, water, steam, air, or animal force? Is the machine itself complicated or expensive? I feel myself very much obliged by the confidence which you have been pleased to

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repose in me, and shall endeavour always to merit your good opinion."

To the extravagant vagaries which occasionally were suggested to him by such projectors, there really were no limits; as when one author, in forwarding to him what he calls his "book on philosophy," observed:-" If the popular or Newtonian system of causes of mundane phenomena and motions are facts, and things are actuated by them as principles, I really am not constituted to hear, see, feel, or comprehend like other persons." A conclusion of the learned writer, the justice of which, (although not exactly in the sense in which he intended it,) probably none of our readers will be disposed to deny!

Of another project that was submitted to him about the same time as the clerical engine generating perpetual motion, which was to supersede all other expedients, we must speak with far greater respect. This was Mr. R. L. Edgeworth's idea of making a cast-iron tunnel across the Menai Strait, instead of the plan Mr. Rennie had then proposed of a bridge. "Our old friend," [Mr. Edgeworth,] says Mr. Keir in December, 1810, referring to this subject, "rides his hobby-horse (Mechanics, &c.) with the same spirit that he did forty years ago." "My scheme is," says Mr. Edgeworth,* "to join the parts of my fourteen-feet cast-iron cylinders in one curve, in a dry dock opening into the Menai; when the joints were sufficiently secured, the whole-let the length be what it might-would float when both its mouths were above water. When properly ballasted, I would open the floodgates of the dock, tow the tunnel into the river near the junction of the opposing tides, and sink it upon a bed, previously constructed, by large stones thrown into the water, so as to form two walls 16 feet asunder, filled with sand thrown between them, and supported by a talus of large stones extending to a considerable distance on each side of the walls. I do not suppose that these walls would, at an average, exceed 5 feet high. Secondly;

* To Mr. Watt, 6th January, 1811.

There is sufficient depth for vessels to pass over such a tunnel during neap-tides. Lastly;-I do not believe that rocks or large stones are driven by the junction of the tides. If they are, it is a serious objection, and most certainly I would not propose anything till I was master of this part of the subject. As to the expense, I suppose that it is not difficult to make a tolerable estimate. The tunnel would cost, at 307. per foot, running, for 1000 feet, only 30,000l. Say 50,000:-it would bear but a small proportion to the expense of a bridge, which is stated at 250,000l. No scaffolding or centres will be wanting; and if it were determined that rocks are not carried by tides or storms through the channel, and if, as appears by Mr. Rennie's report, there is still water, at times, where the east and west tides meet, I do not see any great difficulty that could prevent this vast buoyant mass from floating gently to the place of its destination, nor in its being gradually sunk upon its bed in security. The length of the machine will [not] exceed three times the length of [a first-rate] man-of-war. Your very sincere and very old friend, RICHARD LOVELL EDGEWORTH.”

"I admire your scheme," replied Mr. Watt, "of putting the tunnel together in a dry dock, and floating it into its place; but would not the construction of such a dock prove very expensive? and would not there be great risk of breaking some of the joints or pipes in floating it out, or in laying it upon its bed of sand? which latter would be with difficulty made of the same form as the tunnel.

"I believe no pipe or cylinder of 14 feet diameter has ever been cast of any considerable length, such as 9 feet, nor have I heard of any, even of 3 feet long, beyond 8 feet diameter. They must therefore, as I apprehend, be made in panels, 6 or 8 in the circumference, which infers many joints, flanches, and screws, besides fitting, which is very expensive. Should any part or joint fail after it is under water, repairs seem to me nearly impracticable, except by fishing up the whole. Cast-iron is not perfectly impervious to water when under considerable pressure. B., W.,

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and Co. lined a coal-pit 20 fathoms deep with cast-iron cylinders, 11⁄2 inch thick, in panels, I believe, and the water in many places sprang through the iron where it was apparently solid. Sea-water acts upon cast-iron without dissolving it, so as to change its nature, and to make it more resembling a brittle stone than iron. Bullets fished up out of the Spanish Armada ship, (sunk at the island of Mull,). at the beginning of the last century, were so soft as to be cut with a knife; and I have seen pumps at Wheal Virgin mine, in Cornwall, that by the vitriolic water had, in six years, been reduced to that state. In fresh water it lasts long.

"The expense of such a tunnel I cannot compute, though I believe there are ingenious founders in England who could, so far as the castings were concerned; but that, I should fear, would be the least part of it.

"The tunnel should be laid so low, that vessels, such as frequent that Strait, could pass over it at low water, or at least at any time of the tide that would serve them to come to it, otherwise some unlucky vessel might make a hole in it. I could not hope that the tunnel could be made so tight but that it would take in some water; therefore pipes should be laid within it, and an engine prepared to take out that water as it came in. There are other objections, some of which must have occurred to you, and I would trust to your ingenuity being able to obviate them. On the whole, my opinion remains unchanged, that if such a work is not impracticable, it would be extremely hazardous, and what I could not wish any friend of mine to engage it.

"I trust in your candour to pardon the freedom with which I criticise the scheme. I should consider myself unpardonable, holding the opinions I do, if I disguised them to you. Should you think them not valid, you must place them to the caution of age and my regard for you. I can have no other interest in dissuading you from it.”

...

CHAPTER XXVIII.

MR. WATT IN OLD AGE-HIS PORTRAITURE BY SIR WALTER SCOTT-MADAME RUM-
FORD THOMAS CAMPBELL LOSS OF FRIENDS BY THEIR PREDECEASE-ROBISON,
BLACK, WITHERING, DARWIN-PARTICULARS OF THE DEATH OF DR. BLACK—
GREGORY WATT·
WATT― ROBISON, BEDDOES, BOULTON, PATRICK WILSON, DE LUC-MR.
WATT'S OWN LAST ILLNESS—AND DEATH-OFFER OF A BARONETCY-MONUMENTS
TO HIS MEMORY · WESTMINSTER ABBEY-HANDSWORTH CHURCH-GLASGOW
GREENOCK-LORD JEFFREY'S CHARACTER of him.

THE Wonderful memory of Mr. Watt, at once comprehensive and
tenacious; his judgment, as clear as it was sound;—and the
charms of his conversation, which captivated all listeners with its
"Divine philosophy,"-seem never to have failed on this side of
the grave:-
-a blessing seldom accorded to men of his advanced
age, and not more rare than enviable. If his life opened amid
clouds and storms, it was destined to close in sunlight and calm ;
in his peaceful retirement he had found a refuge, whence he could
bid farewell alike to the illusions of Hope and the uncertainties
of Fortune. He had gained for himself a most honourable place
and name among the greatest and worthiest of mankind; he had
"permanently elevated the strength and wealth of this great
empire; and during the last long war, his inventions and their
application were among the great means which enabled Britain
to display power and resources so infinitely above what might
have been expected from the numerical strength of her popu-
lation."* Thus, in happy quiet, he reaped his large harvest of
"laurels never sere."

* Sir Humphry Davy, when President of the Royal Society; speech at the meeting at Freemason's Hall, 1824.