because the force is concentrated at the joint in the end of the scale beam.

The main feature of the invention, viz. the supposed increased power of the elongated lever, being thus proved to be in error, the other parts of the project scarcely need be noticed; but it may be as well to mention another erroneous part of the scheme. The air vessel or barrel, when at the bottom of the tank, will exert a greater upward pressure, than when near the water's surface; hence a greater power is actually exerted by the buoyancy of the acting vessel in raising the depressed end of the lever, than would be sufficient to depress the vessel under the elevated end of the lever (without considering the effect of friction), but when these two air vessels arrive at the same level in the tanks, their forces will balance each other, and then the beam will rest in a horizontal position.

Novel Enventions.

Snowden's Wheel-way.

A SMALL portion of a wheel-way, upon the plan proposed by Mr. Snowden, (see our Xth vol: p. 337), has just been laid down in the factory of Mr. S., No. 319 and 320, Oxford-street, for the purpose of illustrating to the public the advantages of his new invention.It consists of a hollow trunk of cast-iron, about fifteen inches square and eighteen feet long. This trunk is bedded in earth on each side, for the purpose of giving

it additional stability, and on the top is flat plates of iron, forming a road-way of about twenty inches broad, for the running wheels of the carriage to traverse upon.

The carriage employed for this temporary exhibition is a small car, capable of holding one person, who turns a winch horizontally, for the purpose of impelling the carriage forward. This winch is fixed upon a perpendicular shaft, which passes through the bottom of the carriage, and through the long slit or aperture between the top plates into the trunk below, where a toothed wheel attached to the extremity of the shaft, takes into a rack in the side of the trunk, and by thus turning the shaft with the toothed wheel, the car and the rider are carried along the wheel-way.

This portion of a wheel-way is made the full size that the patentee now intends to construct his trunk, and its wheels, and is intended to shew its superiority over the ordinary kinds of rail-ways, particularly in point of safety, as it is impossible for a carriage to run out of its course, or overturn, however rapid its progress, the impelling agents being confined to the trunk below.

In a circular issued by Mr. S., he says, "This railway (which the patentee denominates a wheel-way), may be distinguished from all others, owing to the machinery attached to the motive force being placed in a track within or beneath the surface of the ground, The safety gained by such peculiarity of construction, is an object of the first moment. Presuming it to be admitted that a travelling steam engine is liable to meet with obstructions, whatever form of rail. is selected-whether with side flanges, a rack on the outside, or an edge-rail— and if driven from its course at a speed of eight or ten miles an hour, (which a pebble-stone or any other slight cause would occasion), danger must ensue. It will be

perceived, by the specimen exhibited, in what manner an occurrence of so serious a nature is intended to be obviated; namely, by the attachment within the track, that renders the regular progress of the moving power, and all the burden connected, perfectly certain.

"The machinery dispenses with a raised rim of any kind, and affords a perfect flat surface for the running wheels: these support the weight of the travelling apparatus, leaving the toothed wheel unencumbered, and freely to act in a straight or curved direction, being kept to the pitch line by the anti-friction rollers coming into use whenever required.

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Having provided for increased safety, it may be necessary here to notice that speed is the next object the inventor has had in view; and he depends on succeeding in this respect, inasmuch, as let the power employed be either steam or that of horses, neither can be used with greater effect in any other plan on a level, and certainly not in ascending an inclined plane, as the means and arrangement exhibited will admit. He anticipates no danger in travelling at the rate of eight or ten miles per hour.

"It is not on the combined effect alone of uniting speed with safety that the inventor comes before the public;-he supposes he has provided a permanency of construction not equalled, and some other minor advantages, which the limits of a circular will not allow of being particularised. These remarks are chiefly confined to that part of the design adapted for the use of steam; and as soon as the new application of horse-power can be exhibited, a fuller description will be given."

Polytechnic and Scientific Entelligence.

ROYAL SOCIETY.

(Continued from page 105.)

Thursday, Nov. 24.-A paper was read, entitled, An Account of the Construction and Adjustment of the new Standard of Weights and Measures of the United Kingdom of Great Britain and Ireland, by Captain Henry Kater, F.R.S.

The author, after stating that the weights and measures of the United Kingdom are founded on a standard, whose length is determined by its proportion to that of a pendulum vibrating mean time in London, which has been ascertained by him to be 39.13929 inches of Sir George Shuckburgh's scale, deems it necessary, on account of the importance of the result, to consider what degree of confidence it is entitled to. For this purpose it is necessary to compare this final result with those ob tained in other experiments, and by different methods. Now it appears that previous to the experiments detailed in the author's paper on the subject in the Phil. Trans. for 1818, on which this result rests, another series is there mentioned, made with the same instruments, but under circumstances which occasioned their rejection, and which, owing to some remains in the instruments between the two series, which occasioned a material alteration in

the distance between the knife edges, have all the weight of experiments made with a different pendulum. The result of these rejected experiments, however, differed only two ten-thousandths of an inch from that ultimately adopted.

The author next compares the lengths of the seconds' pendulum at Unst and at Leith fort, as ascertained by him by an invariable pendulum, whose vibrations had previously been determined in London, and whose length was thus known in terms of the London seconds' pendulum, and as ascertained by M. Biot at the same stations by means of a variety of pendulums, and by a totally different method of observation-that of Borda. The results of this comparison are, a difference between the determinations of M. B. and of the author, of 0.00029 inches in excess at the former station, and 0.00015 in defect at the latter.

From this near agreement of all the results, he considers that the length of the seconds' pendulum in London may be regarded as certainly known to within one tenthousandth of an inch; while from the near agreement of the results of the French and English experiments on the length of the pendulum, he concludes that the length of the metre in parts of Sir G. Schuckburgh's scale may also be regarded as known within one ten-thousandth of an inch.

From an account recently published by Captain Sabine of his valuable experiments for the determination of the variations in length of the seconds' pendulum, he observes, doubts may be inferred of the accuracy of the method employed by him for the observations for determining the length of the seconds' pendulum in London, as well as in those which have been made with the invariable pendulum. It is asserted there, that taking a mean