Judging, however, from practical experience and observation, I am inclined to think that the strengths of the metals are not much deteriorated. My experiments on the effects of temperature on cast iron* do not indicate much loss of strength up to a temperature of 600°. Assuming therefore that copper and wrought iron plates follow the same law, and taking into account the rapid conducting powers of the former, we may reasonably conclude that the resisting powers of the plates and stays of locomotive boilers are not seriously affected by the increased temperature to which they are subject in a regular course of working. This part of the subject is, however, entitled to future consideration; and I trust that some of our able and intelligent superintendents will institute further inquiries into a question which involves considerations of some importance to the public, as well as to the advancement of our knowledge in practical science.

APPENDIX.

In order to test with accuracy the tensile power of the different descriptions of stays used in locomotive boilers, and to effect a comparison between those screwed into the plates and those both screwed and riveted, it was deemed expedient to repeat Mr. Ramsbottom's experiments on a larger scale; and by extending the tests to copper stays as well as iron ones, it was considered that no doubt could exist as to the ultimate strength of those simply screwed, the tensile powers of the stays themselves, and the relative difference between those and the finished stays when screwed and riveted on both sides of the fire-box.

The large lever and requisite apparatus being at hand, the experiments proceeded as follows:

Experiments to determine the Ultimate Strength of Iron and Copper Stays generally used in uniting the flat surfaces of Locomotive Boilers.

*Vide the Transactions of the British Association for the Advancement of Science, vol. vi. p. 406.

It will be observed, on comparing the results obtained from the above experiments, that iron plates and iron stays are considerably stronger than those made of copper. It may not be advisable to have the interior fire-box made of iron, on account of its inferior conducting powers and its probable 1853.

F

durability; but so far as regards strength, it is infinitely superior to that of copper, as may be seen by the following

On the above data, it will be found that the iron stay and copper plate (not riveted) have little more than one-half the strength of those where both are of iron; that iron stays screwed and riveted into iron plates are to iron stays screwed and riveted into copper plates as 1000:856; and that copper stays screwed and riveted into copper plates of the same dimensions, have only about one-half the strength of those where both the stays and plates are of iron. These are facts in connexion with the construction of locomotive, marine, and other description of boilers having flat surfaces, which may safely be relied upon, and that more particularly when exposed to severe strain, or the elastic force of high-pressure steam.

Provisional Report on the Theory of Determinants.
By J. J. SYLVESTER, F.R.S.

I TRUST that I may stand acquitted of any want of respect to the British Association, in having failed to be ready with the Report which last year they did me the honour of confiding to me, on the Theory of Determinants. A circumstance has occurred since the last meeting, which seems to render such report less necessary or useful than at that time it appeared to be, as I have been informed that a complete compendium of all the methods and results of this theory is shortly forthcoming from the hands of a fellowcountryman, Mr. Spottiswoode, in the journal of M. Crelle, which is accessible to the whole mathematical world. This and the pressure on my mind attendant upon multifarious occupations and numerous original researches, may, I hope, serve as a sufficient apology for being unprepared with the report. The much vaster subject of Invariants, which includes the theory of Determinants as its simplest case, has at present no chronicler or editor; and if the Association would think it desirable that a summary of the progress so far made in it should be collected, and be not unwilling to commit to my charge the execution of it, I should have pleasure in accepting the task, provided the period for its completion were previously understood to be not necessarily limited to the period of a single year from the present time.

26 Lincoln's Inn Fields, September 3, 1853.

Report on the Gases evolved in Steeping Flax, and on the Composition and Economy of the Flax Plant. By Professor HODGES, M.D. THE investigations directed by the Association at the Belfast Meeting with respect to the gases evolved in the steeping of flax and the composition of flax straw are in progress, and will be reported at the next meeting. The gases of the fermenting vat have been analysed by the methods of Professor Bunsen, and have been found to consist of carbonic acid, hydrogen, and nitrogen. No sulphuretted hydrogen has in any case been detected. Several analyses of the proximate constituents of the dressed fibre and of its inorganic ingredients have been made, which show that a considerable amount of the nitrogenized and other constituents of the plant are retained in the fibre, even after steeping and dressing have been employed to remove the structures unsuitable for textile purposes.

Thirteenth Report of a Committee, consisting of H. E. STRICKLAND, Esq., Professor DAUBENY, Professor HENSLOW, and Professor LINDLEY, appointed to continue their Experiments on the Growth and Vitality of Seeds.

THE portions of each kind of seed set apart for this year's sowing were from those gathered in 1845, and are consequently of kinds which have been twice, previously, subjected to experiment, first in 1846, and secondly in 1848. The circumstances under which they were sown were similar to those annually resorted to; nevertheless many have failed and appear to be exhausted, or nearly so, as will be seen by reference to the annexed Register :

Remarks.

On the Chemical Action of the Solar Radiations.
By ROBERT HUNT.

[Second Report.]

NOTE. [In the former Report a division was made between the analytical examination of the solar spectrum by absorbent media, and the chemical results obtained from the spectra which had been thus subjected to absorption. It has been found inconvenient, in the examination of the woodcut illustrations, to have constantly to refer from page to page when comparing the chromatic with the chemical effects. This arrangement has, therefore, been altered in the present Report, and the chemical spectrum is given immediately after the description of the luminous spectrum. In all other respects the same order of arrangement is maintained; the numbers attached to the glasses, &c. remain unaltered, and where new specimens have been introduced they have been numbered in continuation. This remark applies also to the paragraphs, so that reference from one to the other, when required, will be made without difficulty. The uncertain state of the present summer, and the small amount of sunshine with which we have been favoured, has greatly retarded the progress of this investigation.]

(70). THE CHEMICAL PREPARATION employed in the series of experiments which I have now to describe, was the iodide of silver as obtained on the ordinary iodized paper, rendered sensitive by the mixture of gallic acid and nitrate of silver. As, however, I find that nearly every variety of paper, and certainly, every different manipulation, gives rise to an alteration in the scale of sensibility, it becomes important that I should describe exactly the character of the paper employed.

A very hard and uniform paper of Turner's was selected; its surface being beautifully pressed, and presenting a fine ivory character. It was first washed with a solution of sixty grains of nitrate of silver to the fluid ounce of distilled water, and dried; then with a solution of thirty grains of the iodide of potassium to the fluid ounce of water. After standing for a few minutes, each sheet was placed in a large vessel of water, and allowed to soak for about half-an-hour. After this, being hung by one corner, it was allowed to dry in a warm room; if the atmosphere was moist, at a short distance from the fire.

This paper was placed upon the screen on which the spectrum obtained fell, after it had been submitted to the action of the medium under examination. Everything being carefully adjusted, the paper was washed rapidly by a wide flat brush, with the following mixture:

Saturated solution of gallic acid

40 drops.

Nitrate of silver, thirty grains to fluid oz. of water.. 10 drops.

The action was, in most cases, allowed to continue for a few seconds only, and the image developed itself slowly in the dark, without any subsequent application of the developing fluid.

(A.) Series of Yellow Glasses (continued).

(71) 60. PURE YELLOW. Colouring matter Carbon.-The visible spectrum is reduced by the violet and indigo rays; the orange blends with the yellow, which is consequently much extended (a slight extension arises also