from thence to London. But not contented with this moderate monopoly, they created the chimera of foreign boats bringing to them the fruits of their labours for the same market. To crown this absurdity they had only to add, that the very fish petitioned for the line, and were so delighted with the project, they would make it a condition of being caught that when dead they should be carried to Folkstone, and from thence to London by the South-Eastern Railway. Now such wisdom might well be excused in a town which is reported to have sent a solemn deputation to the Government to inquire what COLOUR they should wHItewash their tower to render it more conspicuous at sea; but when we see Yarmouth and other towns sharing in the same ridicu lous folly, we cannot help pitying the frenzy of the times, and the poor Parliamentary Committees which have to endure it.

FALL OF TEMPERATURE IN THE ATMOSPHERE AND THEOREM FOR FINDING THE HEIGHTS OF MOUNTAINS.

SIR,

To the Editor of the Railway Magazine.

I WAS much pleased at seeing in your Railway Magazine for March last, a table giving the different decreases of temperature according to different degrees of altitude. I have always considered some such allowance to be made, but there appears to me another allowance or correction that ought to be made, and that is the correction for the natural expansion of mercury according to the temperature, that I make to be at 30° of Fahr. equal to 0001127, or at 100° of Fahr. as equal to 0072012; it is this point that I offer as an apology for addressing you, and I shall be obliged with your opinion on the subject, that is, if the correction for the natural expansion of mercury at any given temperature should be first made, and then the allowance mentioned in your tables; or should the allowance you speak of be first made, and then the allowance for expansion afterwards; for although at first view that may appear no difference, yet in fact there is a great one where considerable accuracy is required. In the measurement of a mountain some years

since in South America, I took four different methods, namely, the common mountain barometer, a mountain barometer on a new plan by Jones of Charing Cross, Wollaston's therometric barometer, and by trigonometry, and yet, strange to say, the greatest difference was only four feet seven inches; but there was a much greater difference in making up the same calculations by Hutton's rule, and that of De Hue, and that of Robinson.

I am, Sir, your humble Servant,
SAMUEL MOYLE.

Queen's Arms Hotel, Poultry.

8th July, 1836.

We do not clearly understand what our correspondent means by the correction for the "natural expansion of mercury," as applied to the fall of temperature given in our table, p. 19. If he alludes to the correction for the barometric columns of mercury in determining heights by the barometer, the barometers must evidently be reduced to the same temperature- that is, the correction for the barometric difference of temperature must be made before any step is taken in calculating the heights. Our method is always to apply the correction to the lower barometer, because it fluctuates the least; and if we are not over nice, we simply multiply 003 by the differences in Fahr. degrees of the attached thermometers, and take the product from the height in inches and decimals of the lower barometer.

The following theorem for obtaining altitudes by the barometer is the one we have deduced from our theory of the universe. It will be found very accurate when its altitudes are corrected for the effects of latitude and vapour. (Laplace's,) with a trifling difference in the mercurial coefficients, flows from it as an approximative theorem.

B, b being the heights of the lower and upper barometers, and F,f the Fahr. temperatures of the air at the lower and upper stations each increased by 448°. The altitude thus found is at a medium to be increased about eight yards per 1000 for the effect of vapour. There is likewise a trifling correction for the decrease of gravity which we have here not noticed.-ED.

THE BRIGHTON RAILWAYS.

STEVENSON'S line, after a contest approaching in expense and duration (eighty days) that of the Great Western, has been thrown out in committee. We repeatedly urged this before, not from any prejudice against Stevenson's line or in favour of any other, but on the broad principle that we did not think in the present state of the case a just conclusion could be arrived at, and the line best fitting Brighton, therefore, at this time, be selected. Brighton is peculiarly circumstanced, and has scarcely a parallel in England besides. Surrounded by a country destitute in our opinion of every attraction, this town has nevertheless risen to the highest point among fashionable wateringplaces. Its Royal residence naturally draws around it the great and the wealthy; its fine air and vicinity to the sea, attract the really ill and others who fancy they are ill; while its easy distance from town crowds it with the families of eminent merchants and opulent tradesmen, and others who are anxious to sink the cares of the week in the bosom of their family at an agreeable place. A line of railway to a town like this, therefore, must evidently be one altogether unexceptionable. If there be any thing pernicious, or inconvenient, or uncomfortable, it will consequently affect the traffic on this line more than it would on almost any other line in the kingdom. When pleasure or health is the object people will not be annoyed, and if they are once they will not submit to it a second time. A bad line, therefore, to Brighton, would certainly fail, and be fatal to the town.

We throw out these observations now the way is clear, that due caution may be exercised in the selection of a line that shall not be objectionable.

Rumours are afloat that Sir John Rennie'scompany are not likely to come again into the field. It is said they have reduced their establishment to one officer only, the Secretary. Mr. Gibbs is once more on the alert, determined, we suppose, to carry his line this time and "no mistake." It is also whispered that a triple alliance between Stevenson's party, Gibbs's, and Cundy's, has been conceived; when it will be brought forth we have yet to learn. Revolutions even more strange are talked of in the engineering department; it is said Mr. Stevenson was, Mr. Walker is to be the engineer.

Brighton is really a very happy place to be the subject of so much contention. Railway winds from all quarters seem to blow towards this one point. A gale has lately sprung up from Oxted hill, which has so exhilirated certain parties as to induce them to talk of bowling all other companies out of the field, and secure to Brighton the benefit of a railway connexion with London via Öxted and Croydon. We shall reserve our opinion on this project to another opportunity, not being at present in possession of all the details.

Amidst all this glorious strife we want to know how far the feelings and wishes of the inhabitants of Brighton have been consulted. We should not imagine there is a great deal of railway knowledge in the town, nor probably will its inhabitants furnish any large portion of the funds for constructing the line, simply because they are not railway speculators. Still, however, they must be the best judges of their own interest; and they have a large stake in the success of any project which is to supersede the present mode of conveyance; for if it be not a good one, farewel to their prosperity. They ought, therefore, to have that respect paid to their wishes to which their interest entitles them, and not to be treated with contemptful neglect. Is it to be endured that the subsistence of a whole town-for it is by their visitors that the people of Brighton subsist--is to be destroyed volens nolens by a set of men for their own private gain, who, probably, neither reside in the town, nor perhaps have any property in it? We here disclaim all allusions to either of the lines of railway; for though some of the plans have been submitted to us more than once, certain details were wanting to enable us to form a decisive judgment on their aggregate merits.

During the progress of the Parliamentary contest, we did think it our duty to remain silent. Now, however, that matters are to begin de novo, we shall feel it equally our duty to watch the proceedings, and just as they appear to us to deserve, so shall we speak of them. We here say nothing of the matter agitated in the House of Commons about purchased partiality, &c. Letters have been shown to us, it is true, of rather a curious cast, but in such a case we confess we do not like to draw inferences; we want that which will need no reasoning-the naked facts.

In looking over the evidence lately given on these lines of the dangers and nuisances of tunnels by medical and other men, we find there is scarcely an idea which we had

not previously published and repeated in our second Number on the "Laying out of Railways." We do not notice this for the purpose of claiming any merit in the ideas, or for being the first to expose the disadvantages of tunneling, but for the purpose of showing our readers, that we are careful what we do publish, and not in the habit of sending forth ideas which will not bear the test of examination.-ED.

Extract from a Letter to the Editor.

"BEING interested in a projected Railway in this neighbourhood, 40 miles long, which will require an inclined plane 20 miles each way, of about 35 to 40 feet per mile, I should be glad if you would give your opinion in your next-as to the practicability of such a line for passengers; viz., as to how many miles per hour a train (of the average number of those that are now going on the Manchester and Liverpool, and with engines of like power) could ascend and descend. I believe the average travelling on the Manchester and Liverpool is about 24 miles per hour, trains and engines of the usual length and power; and I wish to know how many miles per hour the same trains and engines would ascend and descend the incline planes before mentioned.

"There is to be a 2-miles tunnel in the line I am alluding to, which I believe is unavoidable; and as I have seen by your observations that you are very averse to them, I wish to know if your objections would not be much lessened providing they were lit with gas like the Thames Tunnel. Hoping you will excuse these imperfect remarks, I am,

"J. R."

Our correspondent must be perfectly aware, that it is not usual for questions involving calculations to settle a point in which the writer has an interest, to be put to the editors of public journals. If such questions were generally permitted, the editors had need to keep clerks on purpose to answer them. However, as answers to the present questions, in all probability, may apply to other cases we shall give them.

The velocity of ascending either of these planes will be about of that on a level, so that if the velocity on a level be 30 miles an hour up either of these planes it will be only 10. What the velocity may be down rests entirely with the