be effected by means of a feather on the shaft, which is received in a notch made for the purpose, in the head of the reel. The throwing out of gear is done whenever the rope is to be wound upon the reel, which when disengaged from the feather, by being slid back, engages by means of suitable stops or projections, with a wheel and pinion, furnished with a winch, by which the reel may be turned back, and the rope wound upon it.

In order to wind the rope upon the reel I employ a sliding bar, having upon it teeth, forming it into a rack, into which teeth a pinion engages, by which the rack can be moved backwards and forwards. This sliding bar is placed on one side of the frame, parallel to the shaft, and extends from front to back of the machine; its motion is governed by suitable slides. The pinion by which it is moved is placed upon the vertical shaft at the back end of the machine, where it also bears against a friction roller acting on its smooth side. There is a fixed snatch block upon the front post of the machine, and a second snatch block on the inside of the slide towards the spindle, and when the rope is to be wound upon the reel it is first passed round the pulleys of these blocks, when the reel may be turned back, and the rope distributed upon the reel by means of the rack and pinion. For a more perfect understanding of the arrangement of the apparatus by which this is effected, I refer to the drawing, with written references thereto, deposited in the patent office in conformity with the requirements of the law in that case made and provided.

Although I have in the foregoing description spoken of using one spindle only, it is to be distinctly understood that I intend to combine three, or any other number which I may prefer of such spindles, constructed and operating upon the same principle, in the same machine.

What I claim as my invention in the machinery for making ropes and cordage is the manner of distributing the rope, as within described, upon a reel placed upon a shaft or spindle, driven by any of the ordinary means of giving motion to shafts for spinning; which reel is so constructed as to engage and disengage in the manner, and for the purposes herein set forth, whether the same be applied to only one, or to a greater number of spindles in the same frame.

JOHN WHITEMAN.

Progress of Physical Science.

Dissected Battery and Standard Battery of Professor Daniel. For the purpose of ascertaining the influence exerted by the different parts of the voltaic battery, in their various forms of combination, Professor Daniel, contrived an apparatus, which he designates by the name of the dissected battery, and which consists of ten cylindrical glass cells, capable of holding the fluid electrolytes, in which two plates of metal are immersed; each plate communicating below, by means of a separate wire, which is made to perforate a glass stopper closing the bottom of the cell, with a small quantity of mercury, contained in a separate cup underneath the stopper, and with which electric communications may be made at pleasure through other wires passing out of the vessel on each side.*

• The arrangement seems to us much inferior in convenience, to the battery devised for similar objects, by Professor Henry of Princeton, and described in the Amer. Philos. Trans. Vol. 5, Part 2.

Сом. Рив.

A series of experiments performed with the dissected battery is next described; illustrating, in a striking manner, the difference of effects with relation to the quantity and the intensity of the electric current, consequent on the different modes of connecting the elements of the battery: the former property being chiefly exhibited when the plates of the respective metals are united together so as to constitute a single pair; and the latter being exalted when the separate pairs are combined in alternate series. The influence of different modifications of these arrangements, and the effects of the interposition of pairs in the reverse order, operating as causes of retardation, are next inquired into.

In the course of these researches, the author, being struck with the great extent of negative metallic surface over which the deoxidating influence of the positive metal appeared to manifest itself, as is shown more especially in the cases where a large sheet of copper is protected from corrosion by a piece of zinc or iron of comparatively very small dimensions, was induced to institute a more careful examination of the circumstances attending this class of phenomena; and was thus led to discover the cause of the variations and the progressive decline of the power of the ordinary voltaic battery, one of the principal of which is the deposit of the zinc on the platina [or copper] plates; and to establish certain principles from which a method of counteracting this evil may be derived. The particular construction which he devised for the attainment of this object, and which he denominates the constant battery, consists of a hollow copper cylinder, containing within it a membranous tube formed by the gullet of an ox, in the axis of which is placed a cylindrical rod of zinc. The dilute acid is poured into the membranous tube from above by means of a funnel, and passes off, as occasion requires, by a siphon tube at the lower part; while the space between the tube and the sides of the copper cylinder is filled with a solution of sulphate of copper, which is preserved in a state of satuation by a quantity of this substance suspended in it by a collander, allowing it to perco late in proportion as it is dissolved. Two principal objects are accomplished by this arrangement; first, the removal out of the circuit of the oxide of zinc, the deposite of which is so injurious to the continuance of the effect of the common battery; and, secondly, the absorption of the hydrogen evolved upon the surface of the copper, without the precipitation of any substance which would tend to counteract the voltaic action of that surface. The first is completely effected by the suspension of the zinc rod in the interior membranous cell, into which the fresh acidulated water is allowed slowly to drop, in proportion as the heavier solution of the oxide of zinc is withdrawn from the bottom of the cell by the siphon tube. The second object is attained by charging the exterior space surrounding the membrane with a saturated solution of sulphate of copper, instead of diluted acid; for, on compleating the circuit,' the electric current passes freely through this solution, and no hydrogen makes its appearance upon the conducting plate, but a beautiful pink coating of pure copper is precipitated upon it, and thus perpetually renews its surface.

When the whole battery is properly arranged and charged in this manner, it produces a perfectly equal and steady current of electricity for many hours together. It possesses also the further advantages of enabling us to get rid of all local action by the facility it affords of applying amalgamated zinc; of allowing the replacement of the zinc rods at a very trifling expense; of securing the total absence of any wear of the copper; of requiring no employment of nitric acid, but substituting in its stead materials

of greater cheapness, namely, sulphate of copper, and oil of vitriol; the total absence of any annoying fumes; and lastly, the facility and perfection with which all metallic communications may be made and their arrangements varied.

Abstract of Proceedings Royal Soc. in Lond. and Edin. Phil. Mag., May.

On the general Magnetic relations and characters of the Metals. By Professor FARADAY.

In a paper in the number of the London and Edinburgh Philos. Mag. for March, Prof. Faraday has a paper bearing the title just quoted. He states that general views had long since led him to the opinion, that all the metals are magnetic, in the same manner as iron, though not at common temperatures; iron and nickel being no more exceptions to the magnetic relations of metals in general, than mercury is in their relations to heat. He reduced the temperatures of the following metals to 60 or 70° below zero of Fahrenheit's scale, by the evaporation of sulphurous acid, but could perceive no indications of the development of magnetism in them. Arsenic, antimony, bismuth, cadmium, chromium, cobalt, copper, gold, lead, mercury, palladiam, platinum, silver, tin, zinc. Plumbago was subjected to the same result. Prof. Faraday also investigated the temperature at which nickel loses its power of becoming magnetic, with a view to compare it with the corresponding point, for iron which is worked at an orange heat. point was found to be, for nickel, between 630 and 640° Fah. Steel loses its permanent magnetic power suddenly below the boiling point of almond oil; between this temperature and an orange heat it acts as soft iron. The temperature at which polarity was destroyed, appeared to vary with the hardness and condition of the steel. A natural magnet, or loadstone, retained its polarity at a temperature above that at which steel lost the same power, losing it when visibly red in the dark. On the contrary, the same loadstone lost the action similar to soft iron, of becoming magnetic by induction, at a lower temperature than steel. The same results were found when the loadstone of which the magnetism had been destroyed by heat, had its polarity destroyed on cooling, by touching with an artificial magnet.

Abstract from Lond. and Ed. Philos. Mag.

Ice formed at or near the bottom of Streams.

This

The formation of ice in such situations is thus explained by M. ARAGO. --1st. The circumstance already adverted to, that in streams the rapidity of the current, especially in falls, carries down the colder water of the surface, and mixes it with that at the bottom; so that the deepest part here is colder than in still water.

2d. The rough and pointed nature of the substances at the bottom favour the depositon of ice, in the same manner as similar asperities form the nuclei for crystalization in solutions of salts.

3d. The motion of the stream near the bottom is retarded by friction; thus there is less impediment to the formation of the spiculæ of ice.

Mr. Farquharson, in a recent investigation of this subject,t admits that these causes are all in action, but denies their sufficiency to account for the entire phenomena.

He assumes the cause to be, that heat radiates through water; that the same laws prevail with respect to the influence of the state of the surface in promoting radiation, in water as in air. Consequently, the rough surface

* Annuaire des bureau des Long. &c. 1833. † Royal Soc. Trans. 1835, Part I.

of the stones, gravel, &c., at the bottom, enables them to radiate heat, and cool fastest, and there the ground-gru forms.

A writer in a recent number of the London Magazine of Popular Science, after showing the contrariety of the fact assumed by Mr. Farquharson, with the experiments of Melloni, offers the following suggestions:

"There is another distinctive circumstance not adverted to either by Mr. Farquharson or other inquirers, but which appears to us the most efficacious of all others to the production of the phenomena. The adjacent ground, and the bed of the river, are first cooled down by a frost to a lower degree than the water; and thus the bottom will be rather colder than the incumbent strata of water, even in the rapids, where it is soonest brought to an equilibrium of temperature; and this cooling down of the whole adjacent ground, of course, goes on most rapidly under a clear sky, by radiation at night; the ground in the bed of the river acquiring the same temperature, or nearly so, by lateral conduction.

Now solid rock is a much better conductor of heat than loose gravel, or sand, &c., and the former, it appears, composes the bed of the rapids, the latter of the pools. The former, therefore, conducts quickly away the slight excess of temperature in the running water of the rapids, and converts it into ground-gru. The latter conducts more slowly, and has also a greater degree of temperature to carry off; thus--the gru does not form.

Height of Waves. A writer in the Nautical Magazine (Eng.) concludes from his observation of waves after a storm in the Atlantic, that the total height was not less than fifty feet, since "a horizontal line drawn from the apex of the loftiest wave to the ship, would have intersected the main mast about half way from the deck." He gives, further, an estimate founded on the observation which follows:

"A large ship, which was for a short time in company with a frigate we were on board of, was lost sight of at intervals when she fell into the trough of the sea, and only entirely visible when both vessels happened to be on the ridge of the respective waves which bore them up: this alternation of appearance and disappearance continued until we had approached within less than a mile of the ship, for at about that distance, when one enormous wave intervened, she was hid for the last time during the approach. Her elevation from the water-line to her mast-head could not have been less than ninety feet. When both ships were depressed, they were invisible to each other; and when one was on the ridge of a wave, and the other in the trough, part of the masts of the latter were visible to the former.

The distance between the ships, and the relative proportions of the objects, should be kept in mind: a ship compared to one of those billows would be as a mere speck, allowing the breadth of the wave to be half a nautical mile, or 3040 feet; and if we admit the wave to be only twenty feet, the ship's hull thirteen, and five for the height of the observer, the eye, when the ship was on the ridge of the wave, would be elevated thirty-eight feet above the trough in which the other was situated."

Steel for Magnets. Mr. R. Knight concludes that open-grained blistered steel is well fitted for powerful magnets; that closing the grain by heating and hammering it, though it should still remain carbonised, greatly injures it, and that the subsequent action of heat, in opening it, though it much improves the quality, does not restore it to the same openness of grain that it had at first. Trans, Lond. Soc. Arts.

Lines of equal magnetic dip in Great Britain. Mr. R. W. Fox, of Falmouth, has made a number of observations of the magnetic dip and in

tensity in England and Ireland, and lays down from his observations the approximate positions of the lines of equal dip. A remarkable break occurs in these lines in passing from Ireland to England, the line which passes near Dublin, for example, being found on the English coast near the extremity of North Wales, or to the south of the position on the Irish side of the channel. Mr. Fox attributes an important effect on the dip and intensity to trap-dykes, and to basaltic formations; and considers that the usual elevations and depressions of a country modify both of those magnetic elements, elevations increasing the former of them. Third. Ann. Rep. Cornwall Polytech. Soc. 1835.

Temperature of the muscles in Man. By the use of thermo-magnetic arrangements, M. Becquerel has determined the temperature of the muscles in man to be 98.2° Fah. The subjects of experiment were three young men in healthy condition.

Ann. de Chim. et Phys. vol. LIX.

Progress of Practical and Theoretical Mechanics and Chemistry.

On the application of the Hot Blast in the manufacture of Cast-iron. By THOMAS CLARKE, M. D., Professor of Chemistry in Marischall College, Aberdeen.

ratus."

(Read before the Royal Society of Edinburgh, March, 1835.)

Among persons interesting themselves in the progress of British manufactures, it can scarce fail to be known, that Mr. Neilson of Glasgow, manager of the Gas Works in that city, has taken out a patent for an important improvement in the working of such furnaces as, in the language of the patent, "are supplied with air by means of bellows, or other blowing appaIn Scotland, Mr. Neilson's invention has been extensively applied to the making of cast-iron, insomuch that there is only one Scotch ironwork where the invention is not in use, and in that work, apparatus is under construction to put the invention into operation. Apart from the obvious importance of any considerable improvement in the manufacture of so valuable a product as cast-iron, the invention of Mr. Neilson would merit attention, were it only for the singular extent of the improvement effected, compared with the apparent simplicity-I had almost said inadequacy of the means employed. Having therefore, by the liberality of Mr. Dunlop, proprietor of the Clyde Iron-Works, where Mr. Neilson's invention was first put into operation, obtained full and free access to all information regarding the results of trials of the invention in those works, on the large scale of manufacture, I cannot help thinking that an authentic notice of these results, together with an attempt to explain the cause of them, will prove acceptable to the Royal Society of Edinburgh. And that these results, as well as the cause of them, may be set forth with clearness, I shall advert,

1st. To the process of making iron, as formerly practised.

2d. To Mr. Neilson's alteration on that process.

3d. To the effect of that alteration.

4th. To the cause of that effect.

I. In proceeding to advert to the process of making cast-iron, as formerly practised, it cannot here be necessary to enter into much detail in explanation of a process, long practised and extensively known, as this has