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ported the superincumbent earth, and which now bear a considerable additional pressure in consequence of the immense quantity of clay which has been sunk over the crown of the arches, are not displaced in the slightest degree.

On inspecting the boxes or frames at the extreme sides of the shield, it is found that in one the sleepers have been somewhat displaced; and at this spot, therefore, some slight leakage still exists, but not to such an extent as to cause Mr. Brunel any apprehension.

On the first appearance of the leakage, the bricklayers had only partially completed the circle of brick-work which immediately follows the shield; and the cement, so far as they had proceeded, had not properly set, so as to resist the pres-sure of the water; and this portion of the work being washed into the aperture, was necessarily very much increased in size, particularly on the second irruption, when the water came in with so much additional force. The other brick-work is not at all injured.

It is expected that in three weeks the works will be quite cleared of the rubbish which has fallen in, and the work of excavation recommenced.

LONDON

MECHANICS' INSTITUTION.

No. 9.

"The proper study of mankind is Man."

Lectures.

Friday, June 8.-Dr. Birkbeck, on Anatomy; Difference of the Qualities of Motion in Man; Education of the Physical Powers; Greek and Roman Exercises; Grecian Statuary; Developement of Muscle in their Statues; Gymnastic Exercises; Mr. Lutz-Exhibition of the Extraordinary Force of his Muscles; the Gladiator; the Thorax or Chest, its Contents; the Heart, Pericardium, Lungs, Auricles, and Ventricles, their Action; the Adjacent Vessels; Examples-the Human Heart and Ox's Ileart.

Wednesday, 13.-Mr. Stone, on the Stability of Floating Bodies.

Friday, June 15.-Mr. Dufief occupied this evening, by a Lecture explaining the principles of his system in Teaching Languages; he maintained that nature, assisted by analogy, is the best and only guide to direct us in learning tongues.

Wednesday, June 20.-Mr. Stone concluded his amusing and instructive Lectures on the Stability of Floating Bodies, and took leave amid hearty demonstrations of kind

ness.

Friday, June 22.-Dr. Birkbeck, on Anatomy; Particular Description of the Heart; its Beauty, Perfection, and Complexity; its Office in Circulating the Blood; Size of the Tubes; Cavities of the Heart; Direction of the Blood; Force of its Motion; Principal Arteries; Carotid Artery; Marquis of Londonderry; Arteries round the Heart, Head, and Arm; their Complexity and Intertexture; Explanation of the Heart's varied Action; Improvements in Hydraulic Engines; Conjectures respecting Arteries and Veins; the Veins, their Action and Connexion; Notions of the Ancients 'on the Circulation of the Blood; its Discovery by Dr. William Harvey-his Persecutions and Triumph.

Wednesday, June 27.-Dr. Mitchell, on the Architectural Remains of the City of Rome.

Friday, June 29.-Dr. Birkbeck, on Anatomy; Pulmonary or Lesser Frame, Lungs, &c. &c. how formed; its Action, Inspiration, and Expiration; Injurious Effects of Tobacco Smoking; Passage for the Food; the Stomach, its Economy and Minute Description; the Intestines, their Length, &c.; Digestive Organs; the Spleen; Examples of the Liver and Gall Bladder of a Sheep and Lamb; Conclusion of the Structure.

The three last Lectures were illustrated by some beautiful preparations -the veins, &c. being injected; that of the head was a most exquisite specimen. The worthy and excellent President concluded this part of his course with some eloquent remarks on the wisdom of the Almighty displayed in the construction of the

body; and trusted that he had fully proved to the members his opening remark, that " Man is a miracle to man."

The Theatre was this month let for the purpose of a Meeting on the Patent Laws; Major Shaw in the Chair.

I would wish particularly to direct the attention of the members to that part of their last Quarterly Report which states the great decrease which has taken place in the number of subscribers. The Committee, in noticing the fact, observed in substance," that the increase in the subscriptions made up for the want of numbers." The cause of the decrease of members may be attributed partly to the increase of the annual subscriptions from 20s. to 24s.; but the most obnoxious addition is a half-crown, in the name of entrance-money. The resolution for this last was carried in a very different manner from that in which the alteration of the subscription was passed; but few hands were held up for it, and the Chairman paused a considerable time ere he put the question. The Committee themselves had doubts whether it was quite politie to propose it. Both the alterations were proposed at the suggestion of the Sub-Committee appointed to examine the affairs of the Institution. The sum of 8s. 6d., and 1s. for catalogue and rules (making 9s. 6d. before a person can become a member), is an amount large to a working man, and will, no doubt, deter, as it has done, many from joining us. If a proportionate, or even a much smaller decrease takes place each quarter, the Institution will be stranded at once. Would it not have been more advisable to have raised the subscription, and have imposed a fine of 1s. on those who, having been members, had ceased to be so, and again entered the Institution without paying up arrears? It will be seen, on reference to the Report, that there is a falling off in new members of 160! It is not merely the loss of the half-crowns

*See Mech. Mag. No. 187, p. 180. + Ib. page 179.

431

that we are to look to, but the diminution of the influence of the Institution, in proportion as its numbers are diminished. The fallacy of the argument used by the Committee, that the amount of receipts had not diminished, is easily seen through. They must not lay such a flattering and deceitful unction to their souls: they ought rather to be fearful; for, had not this entrancemoney been laid on, we might have had, say 50 or 100, more new members, and their subscriptions would have made the receipts above those of the last quarter. But, as I said before, we are not to look so much to the mere amount of cash, as the interest taken in the Institution by Mechanics; for in this does its welfare genuinely consist. This falling off is the more palpable in reference to its cause, as it has taken place when Lectures of the most attractive and valuable kind are being delivered. I press these few remarks on the attention of the Committee, and of those members who take a leading part in the affairs of the Institution..

It has been long a custom in Livonia, to make cavities in the trees of a forest, for the purpose of receiving and rearing swarms of bees. Some proprietors have hun. dreds and thousands of such trees. Those which are chosen for this purpose are large oaks, firs, pines, alders, &c. It is found that the pure air of the higher regions agrees better with the, bees than the air of hives resting on the ground, in which, owing (it is presumed) to the pernicious exhalations of the earth, disease frequently makes great ravages.-Bull. Univ.

Another "advantage of this plan," says the Editor of the Gardener's Magazine, "is, that it never becomes necessary to kill the bees; and that honey may be taken at pleasure, if it can be spared, during the whole of the summer, by simply removing, or unlocking and opening the slip of board which covers the longitu

432

dinal opening in the cylinder, in the middle of a warm day, when most of the bees are out. This, as we have elsewhere mentioned, (Encyc. of Gard. § 1738), we have seen done every two or three days, for the use of a family, during a residence of above three months in a small Polish town on the Russian frontier."

ADVANTAGE OF BLACKING

GARDEN WALLS.

"Gar

Mr. Charles Harrison, of Wortley Hall, states, in a communication to the Horticultural Society, that he has acquired ten degrees of additional heat, by colouring his garden walls with coal-tar mixed with one pint of linseed oil to each gallon of the tar. The oil is added to obviate the glossy or shining surface which the tar would otherwise produce, and which would be prejudicial to tender leaves and shoots. deners” are very properly cautioned, however, by the intelligent Editor of their "Magazine," against an indiscriminate imitation of this blacking practice; he instances, on the authority of a contributor, the failure of entire crops of melons and cucumbers, owing to "coating the frames with tar." We wish Mr. Loudon had given, at the same time, the rationale of the different effects of an increased heat, when applied to the produce of hot-beds. Is it certain that it was owing to the mere darkening of the colour of the melon and cucumber frames, that such a distructive effect was produced? Might not the exhalations from the tar have had an effect quite independent of the colour? Mr. Loudon adds, that “a blacking, much cheaper" than the one of coal-tar and oil, may be compounded of " lampblack, quicklime, a little copperas, and hot water."

NEW INVENTED TRAVELLING

CARRIAGE.

An ingenious mechanic, a whitesmith named Woodmason, of Dartmouth, has invented a very superior travelling carriage, calculated to accommodate four persons: its construction is simple, and intended to

NEW BLACK DYE AND INK. A M. Honig, of Vienna, has taken out a patent for the following process for producing a new black dye and ink.-Logwood is to be boiled several times in water, and a little subcarbonate of potash added to the decoctions; the quantity being so moderated that it shall not change the colour to blue. The stuff to be dyed, which may be either animal or vegetable, is then to be plunged into this bath: as soon as it is well impregnated with the colouring matter, it is to be withdrawn, and, without being exposed to the air, to be introduced into a solution of green vitriol, and left there until it acquires the desired black hue. In preparing the ink, the decoction of logwood is used in place of the infusion of galls.

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CONSTRUCTIVE CARPENTRY.

BY C. DAVY,

TEACHER OF ARCHITECTURE, &c. LONDON MECHANICS' INSTITUTION.

No. I.

Sir,-Notwithstanding the many excellent works upon this most important branch of architecture, practical men must be well aware that some of the most valuable specimens of construction have not as yet been given to the world; and it is remarkable, that, although we have good roofs, floors, &c. &c. in abundance, so many instances of failure have lately come under notice. I shall endeavour, through the medium of your work, to furnish scaledrawings of constructive carpentry from my own private sketches, and taken from subjects which I considered practically useful, and which have borne a sufficient test of their durability. The one I have first selected consists of a plan and section, showing the mode of constructing a cowl for a malt-house or gra

nary.

Description.

Upon the top of a common hip roof (marked A) is framed an elm curb 6 in. × 5; and round this curb are placed the angle pieces B, which support another curb C of elm, in three 1 in. thicknesses, and 4 wide (these curbs are marked 1 and 2 on the plan); in the centre of these curbs a circular moveable shaft is placed, turning on a pivot at the bottom; the upper part is left square, and bolted to the back of the cowl.

The back of the cowl is formed by six semicircular elm ribs of different diameters, according to the diminution from the bottom to the top. The two at the upper part of the cowl, tinted dark, are bars of iron, as well as a cross bar attached to the middle rib. The reason of this is plain: from the stress occasioned by the inclined position of the cowl, and the action of the wind on those parts, it is covered with battens, as shown in the plan; each being rebated out to receive the other.

The principal one in the middle, and marked No. 3 on plan, is made more substantial, the scant

ling being 5 in. x 3 in.; as it forms a main straight rib for the back of the cowl, and into which the circular elm ribs in the section are inserted (marked D D D). The lever that the wind acts upon projects 10 feet from the circular moveable shaft, and is strengthened in the middle by a feather of oak (shown by two lines) 1 in. thick. Lastly, the circular rim C, at the bottom of the cowl, is strengthened by the radiating pieces of iron, and fastened to a circular collar of the same metal, as shown in the plan.

"The following are the scantlings of the timbers belonging to the roof of this building :Wall plates Angle ties

5 × 5 do. do.

Principal rafter. Tie-beams

8

× 7 top x 6

10

× 8

ON SMOKY CHIMNEYS.

BY MR. JOHN SMITH.

(Concluded from our last, p. 422.)

It must be evident, as before stated, that the wind, coming in contact with the upper surface of each conical cap, will be diverted in an upward direction, and would consequently escape upwards, if not obstructed; but meeting immediately with a repulse, it returns, and a conflict takes place; and, as the wind constantly presses, it must escape at the opposite side or down the chimney. The more violent the wind, the greater portion will be diverted down the chimney; as, the force being greatest from without, more wind will gain admittance at one side in an instant than can in the same instant discharge itself through the other side, in consequence of the diminished force and conflicting currents within. This will, of course, escape at the greatest aperture, which undoubtedly will be