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at rest. It will be particularly gratifying to the man of science, as it enables him to have always at hand a constant power for the investigation of its properties, without any labour of preparation. We notice among the beautiful results of this machine, that it charges an electro-magnet so as to sustain a weight of one thousand pounds, and it ignites to a white heat large platinum wires, and may be used successfully for blasting at a distance; and should Government ever adopt any such system of defence as to need the galvanic power, it must supersede the battery in that case. Professor Page demonstrates, by mathematical reasoning, that the new contrivance of the coils affords the very maximum of quantity to be obtained by magnetic excitation.-Report of American Commissioner of Patents for 1844.

NOTES AND NOTICES.

The "satisfactory" Janus.-The Times of Thursday last, in giving an account of a visit of the Lords of the Admiralty to Chatham, states, that their lordships, after inspecting the Dockyard, "proceeded on board the Janus steam sloop, and proceeded under steam down the river, followed by the Black Eagle Admiralty steamer. The rate of the speed of the Janus was about three miles an hour, the wheels revolving about five times in a minute. On its arrival at Gillingham-reach, their Lordships seemed to have had enough of the vessel, for they left it, and proceeded on board the Black Eagle to Sheerness."

Ice-land transformed into Sun-land.-M. Gaymard read to the French Academy of Sciences, at one of their recent meetings, a letter which he has received from Reykiavik, in Iceland, informing him that for an entire year there had been beautiful weather in that island, and scarcely any winter. The summer of 1844, and as much of the present summer as had passed, have been delightful. The meadows are in the finest possible state, and the fisheries highly productive.

Collon spinning in America.-The Boston Transcript says, "The new cotton-spinning frame, just put into operatión at Lowell, we understand, is creating quite an excitement among manufacturers. It is said to require but one half the power, and will make more yarn, and of more even twist, at about two-thirds the expense of the other kinds of frames in use."

An American Locomotive-Poor Oliver Evans's prophecy is being more than realized, concerning the rapidity of transmission by railroads. Perseverance, inventive genius and mechanical skill have fashioned that strong propelling power, the locomotive engine, to almost a state of perfection, and little remains to be done, it would seem, to add to its usefulness, or increase its strength. Of re cent date in their invention, their progress to enlarged usefulness has been almost as rapid as their flight from point to point; and what was but a few years ago a comparatively slow-moving, illconstructed machine, now starts upon its errand with a rapidity and a precision of movement, that seems almost instinct with life. We thought something like this, on Saturday, when looking at a powerful engine, called the "Jacob Little," which was brought down from the city railroad, from Mr. Norris's manufactory, for the purpose of being shipped to the Long island railroad, upon which it is to travel. We were informed that it was built with the purpose of carrying three hundred passengers

and the United States mail from Brooklyn to Greenport, (L.I.) a distance of ninety-seven miles in two hours and a half! and we are assured that the machine could accomplish it in two hours only-a rate of forty-eight miles an hour. Certainly this is speeding upon the wings of the wind. The arrangement of the locomotive differed from others we have seen. In front, the usual four wheeled iron truck, played upon a pivot to permit a free undulatory motion, and next them was a single pair of driving wheels of the unusual dimensions of five feet ten inches in diameter-These two driving wheels supported five sixths of the weight, and immediately behind them under the engine's platform was a pair of small wheels of the same diameter of those of the truck, which bore the remaining sixth of the burden. The relief wheels were not geared to the large driving wheels. The diameter of the cylinder was ten and a half inches, the length of stroke twenty inches, and the whole weight of the Engine almost fourteen tons.-U. S. Gazette.

LIST OF PATENTS GRANTED FOR SCOTLAND, FROM THE 22ND OF JUNE TO THE 22ND OF JULY, 1845.

Robert Addison, of Regent-street, Middlesex, piano-forte manufacturer, for improvements in piano-fortes. (Being a communication from abroad.) Sealed, June 23.

Charles Smith, Newcastle-street, Strand, London, gent., for new and improved methods in the construction and application of a variety of cooking, culinary, and domestic articles and utensils, some of which are applicable to cleaning and a variety of similar useful purposes. June 24.

James Johnston, of Willow-park, Greenock, Esq., for new and improved processes in, and machinery for, making and refining sugar. June 26.

Auguste Cherot, of Nantes, France, spinner, for certain improvements in machinery for spinning flax, hemp, and other fibrous substances. (Being a communication from abroad.) June 30.

Charles Wheatstone, of Conduit-street, Middlesex, Esq., and William Fothergill Cooke, of Kidbroke near Blackheath, Kent, Esq., for improvements in electric telegraphs, and in apparatus relating thereto, part of which improvements are applicable to other purposes. July 3.

David Gavin Scott, of Cromwell-park, Perth, for an invention by which the heddles of a loom are moved to produce various patterns on Woven fabrics. (Being a communication from abroad.) July 4.

James Kite, of Hoxton, Middlesex, coal-merchant, for certain improvements in constructing chimneys, and in the means used for sweeping the same, part of which improvements are applicable to other like useful purposes. July 4.

Patrick Sandeman, of Greenside-place, Edinburgh, for improvements on coffins. July 9.

William Mather and Colin Mather, of Mather Salford, Lancaster, engineers, for certain improvements in boring earth, stone, and subterraneous matter, and in the machinery, tools, or apparatus applicable to the same. July 10.

Henry Pinkus, of Mount-street, Grosvenorsquare, Middlesex, Esq., for improvements in obtaining and applying motive power in impelling machinery. July 17.

Joseph Amesbury, of Devonshire-street, Portlandplace, surgeon, for improvements in apparatus for the relief or correction of stiffness, weakness, or distortion in the human body. July 18.

Thomas William Gilbert, of Limehouse, Middlesex, saiaker, for improvements in the construction of sails for ships and other vessels. July 18.

Alexander Wright, of South Lambeth, Surrey, for improvements in gas meters. July 21.

*

SIR,-In Vol. xxxix. of your Magazine, p. 309, was given the history of the dredging machine, extracted from Part I. of Weale's "Quarterly Papers on Engineering," in which it is stated that the late Mr. Rennie was the first to propose and construct a dredging machine, to be worked by steam_power. "In the year 1802, the late Mr. Rennie, in his Report to the Hull Dock Company on the best mode of improving the docks, proposed applying the six-horse engine, then employed for driving the piles of the coffer-dam of the entrance, to the old dredging machine of Grimshaw. . . . The machinery was fixed in a barge 61 ft. 6 in. in length, and 22 ft. 6 in. in width, and draught of water 4 feet; it worked in a depth of 14 feet until the year 1814, when various alterations were made in it under the direction of the late Mr. Rennie, who caused the sixhorse engine to be erected in it in the year 1804-after which it raised from 20,000 to 23,000 tons of mud per annum, at a cost of about threepence per cubic yard, from a depth of 22 feet." It therefore appears that Mr. Rennie's machine, for which priority is claimed, was proposed in 1802, and erected in 1804; what follows will, however, show that the late Sir Samuel Bentham, in the year 1800 (two years before Mr. Rennie) invented and recommended such a machine to the Lords Commissioners of the Admiralty, which recommendation having been approved of, it was made, and being completed by April 1802, (two years before Mr. Rennie's), was put to work, and found fully to answer the purpose for which it was constructed.

As so much discussion has arisen as to whom the merit of this important invention is really due, I trust that the following details collected from official documents, most of them existing at the Admiralty, together with a description of the machine, and reduced copies of the original drawings from which it was constructed, will be found acceptable to your readers.

It appears, that as early as the year

That is, a dredging machine with buckets, Messrs. Boulton and Watt having only applied the steam-engine to the old spoon machine.

1799, Sir Samuel Bentham had directed his attention to this subject, and having collected data on the system of dredging then in use, subsequently devised a machine for performing the operation more speedily and economically; and in the early part of 1800, he addressed the following letter to the Admiralty upon the subject:

"Portsea, April 18, 1800. "Sir,-Among the various inconveniences to which his Majesty's several naval establishments appear to be subject, no one local circumstance seems to cause so much hindrance to the business of them as that of the want of a sufficient depth of water at the wharfs, and other parts of the harbours, contiguous to which these establishments are placed. I have, therefore, been led to consider the laborious operation of digging up ground from under water, as affording an instance in which the introduction of machinery, to be worked by a less expensive force than that of manual labour, would be productive of the most extensive utility.

"The apparatus used by persons under the direction of the Trinity House, seems as well adapted to the digging up ground under water as any engine to be worked by manual labour can be expected to be; but the effect of such an apparatus is so inconsiderable, that the attempts of clearing away by these means some particular shoals in the river Medway have been given up, and though a similar apparatus is, from necessity, now used in Portsmouth harbour, for the purpose of keeping clear the jetties, as well as the entrances to the docks and basins; yet, as the expense of the manual labour alone, for the doing the little work of this kind that is done there, amounts to about 1,4007. a-year, being at the rate of 2s. 6d. per ton, I could not venture to propose the undertaking any considerable works for the improvement of the harbour by any such expensive means.

"At Hull, as well as in Sweden and in Holland, an apparatus for digging up ground from under water has been worked with great effect by means of horses; but the force of a steam-engine being materially cheaper, as well as more convenient, seems far preferable for any such work as this.

66

By a well-contrived apparatus for this purpose, worked by a steam-engine, I am of opinion that, at a very moderate expense, not only all shoals formed by a gradual accumulation of soil, may be cleared away, to the great benefit of rivers and harbours

116

height of even high water mark, without the assistance of manual labour for any other purpose than that of transporting the vessels loaded with the soil to and fro.

"I have for these reasons been induced to bestow a good deal of attention in the contriving an apparatus for the digging up, removing away, and depositing ground, according to a variety of local circumstances, and would, therefore, take the liberty of proposing, that my Lords Commissioners of the Admiralty would be pleased to give directions for the preparing such an apparatus for the use of Portsmouth Harbour, where the want of it seems most pressing. "The expense, as near as I can estimate it, would be as follows:

"For the millwright's work, including the steam-engine and other machinery, adapted to raise about 1000 tons of soil a day.. "For a vessel on which the machinery would be fixed, as well as for others adapted to the carrying away the soil, and depositing it either out in deep water, or on new made ground.....

£ s. d.

1,200 0 0

3,500 0 0

"In case their lordships should approve of this proposal, I would request that they would be pleased to authorize me to cause the machinery to be prepared immediately, under the direction of Mr. Goodrich, the mechanist; that with respect to the vessels, the officers of this Dockyard should be directed to take my instructions respecting them; and that they may be built in the Dockyard, or by contract in the neighbourhood, as may appear most economical. "I am, &c.,

"S. BENTHAM. "To Mr. Secretary Evan Nepean." To this letter the following reply was received:

"Admiralty Office, April 23, 1800. 'Sir,-Having laid before my Lords Commissioners of the Admiralty your letter to me of the 18th instant, proposing that directions may be given for preparing an apparatus for the purpose of digging up ground under water in Portsmouth Harbour, I have their lordships' commands to signify their direction to you to furnish them with drawings of the machinery and vessels which you propose should be constructed for the purpose above-mentioned.

"I am, Sir,

"Your most humble servant,
"EVAN NEPEAN.

"General Bentham."

Sir Samuel Bentham accordingly furnished the plans and estimates required, as appears by the following letter:

I

"Portsea, May 13, 1800. "Sir,-In obedience to the commands of my Lords Commissioners of the Admiralty, contained in your letter of the 23rd ult., herewith enclose a plan, section, and elevations of the vessel and machinery proposed for the digging and raising of soil from under water, as also plans, sections, and elevations of the barges proposed for depositing the soil under different circumstances; and as the economical execution of various important works depends on the bringing this apparatus into use, I would request that, in case their lordships should be satisfied of the expediency of it, they would be pleased to give me authority for the preparation of the machinery accordingly, and that directions may be given for the building of one of each of the vessels in this Dockyard, after which a greater number may be built, either there, or by contract out of the yard, as may appear most economical. "I am, &c.,

"Evan Nepean, Esq."

"S. BENTHAM.

The matter having been taken under consideration by the Lords of the Admiralty, Sir Samuel Bentham's suggestion was approved of, and he received the following official communication upon the subject:

"Admiralty Office, July 30, 1800. "Sir,-My Lords Commissioners of the Admiralty having referred to the Navy Board your two letters to me of the 13th and 20th of May last, respecting an invention for digging up and carrying away soil from under water, I have their lordships' commands to send you herewith a copy of a letter which I have received from the Navy Board, for your consideration; and to desire you will let me know, for their lordships' information, if the engine therein alluded to can in this instance be brought into use. "I am, Sir,

66

"Your humble servant,
"EVAN NEPEAN.

' Brigadier-General Bentham."
The following is the letter from the

*So convinced was Sir Samuel Bentham of the value of the new machine as to saving useless expense, that he wrote to General Ross (20th August, 1801), then directing the Ordnance works at Portsmouth, recommending that the works on the south side of the gun wharf (mentioned in the proposal to the Admiralty)" should be desisted from for the present, until the machine which is now making for digging soil under water be completed."