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259 this astounding machine works is as follows. The message is originally written on a conducting material, such as tin foil, with resin or some non-conducting ink. Over the face of this letter, which is placed on a cylinder, a point of metal revolves—this point is in connection with the conducting wire; at New York say, a piece of chemically prepared paper is placed on a like cylinder to receive the message; both cylinders are made to move round by clockwork. As the point at this end of the wire passes over the non-conducting resin writing no current passes, hence the point which moves synonymously with it at New York does not change the colour of the paper, but all the other surface of the writing tablet being a conductor, the currents pass and deepen its colour by chemical action on the far-distant recording tablet. The receiver thus obtains a perfect fac-simile of his correspondent’s handwriting done in white upon a blue ground. Specimens of this electrical handwriting are placed beside the telegraphic machine, and afford an admirable example of the caligraphycalligraphy [sic] of the lightning pen.

The great practical puzzle of the present day—submarine telegraphy—endeavours to find its solution in dozens of different specimens of electric cables. When it is remembered that the problem to be solved is to produce some envelope which shall perfectly isolate and protect a conducting wire, running for thousands of miles, as the Atlantic cable for instance does; when it is further remembered that a fault in the covering material of the wire only as big as a pin-hole speedily becomes enlarged to the size of a sixpence by the burning action of the electric fluid passing out into the water; when, again, we find the gutta-percha, with which cables are covered, is liable to the attacks of insects, to be abraded by rubbing on sharp rocks; and when we find that in shallow water cables are always liable to be dragged up by ships’ anchors, the difficulties of making them electrically secure are indeed immense. Hence hundreds of patents have been taken out to accomplish the desired end, and thousands of miles of ruined cable, representing some two millions of money, now lie at the bottom of the ocean, subjects of great curiosity no doubt to the fishes.

We have been noticing hitherto different forms of the great inventions which have changed the face of society within the last quarter of a century; but the museum does not shut its doors to ingenuity employed in even the smallest objects. Here, for instance, is a collection of ancient and modern locks,—some of Chinese, some Indian, and some Egyptian origin, all giving testimony to man’s familiarity with this little instrument before the Christian era. In these, all the leading features of the tumblers in our best locks are to be found. The Indian padlock may be said to depend upon its security for its moral influence! It is made in the form of a bird, representing the Hindu deity Garuda. The works are of the most trumpery kind; but it is supposed to owe its security to a fear of the vengeance of the deity whose image it represents. As a pendant to this moral lock, are the keys poetical, which once gave freedom to Mary Queen of Scots from Lochleven Castle.

Sewing machines of all kinds are here, of course; but we were struck with an invention calculated, we think, to give relief to the needlewoman in a still more marked manner. A machine to mend stockings has always struck us as a great desideratum: our inventor, however, professes to accomplish his object in a more expeditious manner. Noting that stockings wear out only in two places, at the toes and heel, he manufactures these pieces at a cheap rate, in order that they may be pieced on at home.

Another ingenious man has patented a sweeping brush, which runs along the carpet on rollers, and collects all the dust in a covered box. The advantages of this machine are, that it does its work without scattering the dust on the furniture; therefore the housemaid need not cover it up while pursuing her cleansing work.

Another individual, who still further labours to ease the domestic servant, exhibits a patent for peeling potatoes and apples, and for mincing meat; and the gas engineers show working models of different gas stoves, which supersede the use of coal fires altogether.

The introduction of new materials, and the cheapening of old ones, has given rise to their applications in articles with which their use would, on à priori grounds, appear totally inadmissible. Here, for instance, is a glass pump, working with an india-rubber valve; and it seems strong enough to resist any ordinary rough usage. Close at hand is a mangle, the bed and rollers of which are made of the same fragile material.

The introduction of india-rubber has, we know, revolutionised whole trades, and the glass-cases in the museum are filled with specimens of the purposes to which, under different forms, it is applied.

Sedulously masticating a piece of india-rubber, in order to make bladder-pops in our school-days, how little did we dream that the sticky mass was destined to play the part in the world it has done during the last quarter of a century. The many waterproofing purposes to which Messrs. Mackintosh have applied it, we are all familiar with, and the change which takes place in its nature on the application of a little sulphur, we also know; but the public, unless they visited the museum, would scarcely dream of the extent to which its consequent increased resiliancy has caused it to displace the use of steel in the form of springs, and of packing of all kinds, in order to make air-tight joints.

Yet another change is induced in this Protean material: by simply baking it, we get what is termed ebonite by the Messrs. Silver, its discoverers and patentees. This substance has all the appearance of jet, with this advantage, that it is tough instead of brittle; hence its applicability to a thousand uses in the arts and sciences. We see here chains which cannot be told from the best jet, combs, paper knives, statuettes, anything, in short, which can be moulded, and requires a high finish and polish. These specimens of the manufactures carried on at “Silver Town,” in the Isle of Dogs, are full of the deepest interest, and prove how quickly many of our oldest established trades may be prostrated by the discovery of some new material, or the chemical change which may