BY JAMES GLAISHER, ESQ., F.R.S.

His GRACE THE DUKE OF NORTHUMBERLAND proposed in 1859 to the President of the British Meteorological Society, THOMAS SOPWITH, Esq., M.A.,F.R.S., the establishment of Meteorological Observations at the several fishing-villages on the coast of Northumberland. The primary object of His Grace was the saving of life and property, by such a foreknowledge of the weather as can be obtained by means of accurate barometrical and meteorological observations, and Mr. SOPWITH and the Council of the Society have since used their best exertions to forward, as much as possible, the plans suggested by the enlighteaed benevolence of His Grace.

Instruments were accordingly ordered, and at the beginning of last September, they being ready, I proceeded to Berwick-on- Tweed with Mr. SOPWITH, to facilitate the objects in view. Here we received every attention from the Rev. G. H. HAMILTON, the vicar of the town, the Rev. Messrs.

IRWIN and DURHAM ; ALEXANDER LOWRY, Esq., and SAMUEL SANDERSON, Esq., the Hon. Secretary of the Berwick NATIONAL LIFE-BOAT INSTITUTION Branch. To Captain POPPLEWELL, R.N., our best thanks are especially due, for the very kind interest he took in the subject, and for visiting with me every station from Berwick to Hauxley, which conduced most materially to my success.

So also I am indebted to C. W. McKERLiE, Esq., and W. DICKSON, Esq., of Alnmouth; also to J. MILLER, Esq., Coast-guard Chief Officer of Tynemouth; and to Major POTTER, the Mayor of Tynemouth, for very effective assistance, and to all persons of the Coastguard, and in the service of the NATIONAL LIFE-BOAT INSTITUTION on that part of the coast.

The adopted number of stations is fourteen : the most northern is at the Greens, North of the Tweed; one at Spittal, South of the Tweed, one on Holy Island; the others at North Sunderland, Beadnell, Newton, Crastor, Boulmer, Alnmouth, Amble, Hauxley, Newbiggin, Cullercoats,and North Shields, which is the most southern station. At all these places the barometer is placed in public view, for the most part in a Window, situated very near to the place where the fishermen collect, so that every one may see it at all times.

All the instruments are plain and strong, easily read, and not easily injured. The makers were Messrs. NEGEETTI and ZAMBBA, who are well known for the accuracy and excellence of their work. They were all examined by myself, and their accuracy tested.

Among the fishermen I found an earnest desire to understand the barometer: some of the more intelligent put questions to me as to its construction, and some as to the principle of its action, and others as to the use of the vernier, and how it was used.

The habitual use of any instrument in the ordinary purposes of life, too often engenders a neglect of the principles on which it acts, and among such instruments is the barometer, an instrument whose action depends on principles as beautiful as any in the whole range of natural science. I will therefore say a few words upon the principles of constructing a barometer, the use of the vernier, and how to read it in connection with the barometer scale.

The first step in such an inquiry must be connected with the atmosphere by which we are surrounded, and the variations of which, in weight, the barometer is designed to measure.

The atmosphere is an invisible elastic fluid, possessing, among other qualities, that of weight. To most persons it is a matter of wonder that air possesses weight. Yet if we reflect that clouds, which are composed of water, and therefore possess weight, are upheld by the air beneath, and which, therefore, must be mass for mass heavier than the clouds, we cannot fail to perceive that the air must possess weight. Again, we know a balloon with its car and heavy appendages ascends in air; the only reason for this must be, that the bulk of atmospheric air is heavier than an equal bulk of gas which is contained in the balloon, in addition to the weight of the balloon itself and its appurtenances. It is not easy to weigh air, yet it has been done; and the weight of 100 cubic inches of air, when the barometer reads 30 inches and the thermometer stands at 60 degrees, is found to be about 31 grains. This is about one eight hundred and fifteenth the weight of the same bulk of water, and therefore air is about eight hundred and fifteen times lighter than water. Air thus possessing weight, it follows that that portion nearest to the surface of the earth is pressed by all that which is above it.

If we take a glass tube nearly 3 feet in length closed at one end, filled quite full of mercury, and then place the open end into a basin of mercury, preventing the admission of air into the tube, by covering the open end with the finger till it is covered by the mercury in the basin, then on removing the finger and placing the tube vertical, the mercury in the tube will sink to the height of about 30 inches above that in the basin.

Now the mercury in the basin within the tube is pressed by a column of mercury 30 inches high, and on every other part outside the tube by the atmosphere above it, and these two balance each other. The weight of the column of mercury in the tube can be weighed, and it will be found that if a column of mercury one inch square and 30 inches high be weighed, it will be about 14$ Ibs., and therefore a column of air one inch square, and reaching from the earth to the top of the atmosphere, will weigh about 14i Ibs.

As the mercury in the tube exactly balances the pressure of the atmosphere, this 'height will vary in proportion to its variations in pressure, and the height of the mercurial column in this climate is found to vary from less than 28 inches to 31 inches at the sea-level.

Thus it will be seen that at one time the height of the column of mercury may be three inches greater than at another time, this implies that at one time we may have one-tenth less air over us than at other times.

The mercury will therefore rise and fall in the tube and whenever it falls, the surface of the mercury in the basin or cistern will rise; and whenever the mercury in the tube rises, the surface of the mercury in the cistern will fall; and, therefore, the point 30 inches marked on the barometer scale is not always exactly 30 inches from the surface of the mercury in the basin or cistern.

The cisterns of the barometers prepared for the coast of Northumberland and for the life-boat stations are of that capacity in relation to the diameter of the tube, that the change of height in the surface of the mercury in the cistern corresponding to a change of height of 3 inches of mercury in the tube is less than one hundredth of an inch, and therefore, as the readings are only to be made to this degree of accuracy, this error in these barometers is insensible.

The essential part of every barometer is a glass tube filled with mercury; all the other parts of a barometer are conveniences to determine accurately the height of the column of mercury in the tube above the surface of the mercury in the basin or cistern. In filling the tube, much care and many precautions are necessary, and the mercury must be boiled in the tube itself throughout its whole length.

The scales of the barometers are divided into inches, and each inch is divided into ten parts; therefore each small division on the barometer scale is one-tenth of an inch.

A small scale, moveable up and down (by means, of the milled,head shown as a white spot in the annexed engraving, just below the scale,) along the edge of the barometer-scale, called a vernier, is to divide one of the small divisions of the barometer scale into as many parts as the vernier scale itself is divided.

The vernier is divided into ten parts, numbered 1, 2, 3, 4, 5, 6, 7, 8, 9, 10; and enables the reading of the barometer, or height of the. mercurial column, to be taken to one-hundredth of an. inch. In some barometers for the life-boat-'stations the alternate div-isipns on the vernier only are numbered—thus, 2, 4, 6, 8,.,j'0; the zero and the odd or'intermediate numbers being very readily inferred. Now to read the barometer, first adjust the eye by means of the fore and back part of the lower termination of the vernier at an exact level, and while so placed bring the lower part of the vernier to the highest part (its apex) of the mercurial column. Next look to the zero of the vernier, and see where it is placed with respect to the barometer scale. Suppose the zero line (the line next below that numbered 1 on the vernier) and the line 29*0 on the barometer scale, to.be in the same straight line,,then the reading would be 29-00 in.; and in like manner, if the zero line be coincident with the barometer scale, At 29 • 1 the reading would be 29-10 At 29-2 „ 29-20 At 29-3 „ 29-30 and in the same manner all readings are to be taken, when the vernier zero and a line on the barometer scale appear to be in the same straight line.

Now, suppose the zero line of the vernier not to be coincident with any line on the barometer, but to be situated between two of them, which will generally be the case, then some other line on the vernier will coincide with one on the barometer scale.

Suppose the zero of the vernier be between 29 • 50 and 29 • 60 on the barometer scale, this shows the reading is greater than 29 '50, but not so large as 29 '60; on looking up the vernier, suppose the line numbered 3 be found to be coincident with one on the barometer scale, this shows that 29 '50 is to be increased by three hundredths, and the reading would be 29'53 in.

In like manner all readings would be taken when the vernier zero is situated between two lines on the barometer scale, namely, by ' increasing that reading of the barometer scale, which is next below the zero of the vernier, by that number on the vernier a continuation of whose line appears as one of those on the barometer scale.

These readings are to be taken once at least on every day, twice when convenient, and even more than twice on occasions of either a rapid fall or rise in the mercurial column. They will be registered and transmitted to me at the end of every month.

On taking the reading every morning a dot will be placed on a ruled scale, as shown in the following diagram, corresponding to the reading, and a line drawn from the last dot to the new one, and thus successively day by day from one point to the next, indicating to the eye the changes of the preceding days, These diagrams will be publicly exposed side by side with the barometer, and thus remain till the seventh day of the following month. Any one looking at them would at once see what the barometer readings had been, and the tendency of future weather.

If there be found but small deviations from a horizontal line, and the barometer reading still nearly the same, a fisherman would know that no change was probable, and go out to fish without hesitation. If, on the other hand, he found the diagram ex- , hibiting an ascending or descending line, he A 1 % eo w sii th SPECIMEN OP A DAILY BAROMETER DIAGRAM FOR NOVEMBER, 1860.

g M !— ! eo 3 Ci W 00 M O. M o N ifl N 3 eo n w N rH C J O M 0 r4 GO rH rH S in I-H ** r—i en r— ! IN rH rH rH O ft O co t» O iO F M M rH 1 o c: e 0 o OC - O 00 c fcs - 0 IN C « - C£ to o tf! - 010 0• » - o oo 0« o $1 / o M o H / o 1- o c O C O C9 ( f / } I ] §1 ow O W / t / t gi O b* / V / o t* o / S / • / o '-C 01ft / S r s / O O 0• f + / s '' ** ( f j t erfr o M s / _ -•.

J J 0 M O C Ip •? s oei o r 0 H 6o 3J 4* O O Q W ould know that there had been a progresre rise or fall, and comparing this with e then state, and with his local knowledge of the coast, he would be enabled to judge with much confidence whether fair or foul 'weather was to be expected, and, consequently, whether it would be prudent for him to go out or remain on shore.

A fisherman examining the state of the barometer need not notice the vernier at all; but may pass his eye at once from the top of the mercurial column to the barometer scale; or he may limit his observation to noticing whether there be a space between the lower part of the vernier, or the projecting piece across the tube, and if there be, it will show that the barometer reading has fallen since the regular observation, and if there be not, it will show that it has either continued stationary, or that it is rising, by which indications, in conjunction with the diagram, he will accordingly be guided.

The diagram annexed is for the month of November just passed. An inspection will show that, till the 5th day, the deviations from a horizontal line are very small; then there is an ascending line to the 7th, when the highest point in the month is reached; from this time till the 12th, the barometer reading was constantly decreasing; on the 13th day, there was scarcely any change; on the 14th, two points are laid down, as the reading decreasing from 29'46 in., in the morning, to 29'28 in., in the evening; on the 15th, the lowest reading in the month took place; on the 16th, the reading was steady all day; it then decreased during the night to 29 • 20 in., on the following morning; there was a rise of half an inch between the 17th and 18th; and the increase continued till the 19th; there was then a decrease to the 21st; and alternately an increase and decrease about the point 29'5in., till the end of the month.

Now if day by day such curves be laid down, and be watched in connection with the direction of the wind and the Barometer Instructions by Admiral FITZROY, F.R.S., they will certainly tend to save many lives, and to preserve much valuable property from destruction.

Those barometers of known character will not only serve the purpose intended, but will also be available for determining the errors of all barometers in their vicinity; by allowing O'l inch (one-tenth of an inch) less reading for every 100 feet of elevation.

I may here remark that in my journey I found but one barometer reading correctly, viz., that at Beadnell; and the fishermen there had no confidence in this instrument in consequence of the rack-work of the vernier being out of order, and the instrument not in charge of any one: all other instruments were in error from 0 • 3 inch to 0 • 7 inch, and one was as much as one inch.

The object of a personal visit to every place was to see that every instrument was in a fit state for observation after its journey; that it was put up properly and in the best place the locality afforded, and that I should see the fishermen, and give personal instructions to them, and particularly to those with whom the instruments were left in charge.

The observations are also to include temperature of the air, direction of the wind, fall of rain, and state of the weather; but of these I will not further speak in this paper.

One of the most gratifying results of my visit is the being able to say that the fishermen -generally along the coast have showed not only a friendly reception of the instruments, but an intelligent appreciation of their use; and I am glad to say that these were evinced by expressions of gratitude and respect, which I believe to have been truly honest and sincere.

All who have examined those sad memorials contained in the Wreck Charts, published by the BOARD OF TRADE and the LIFE-BOAT INSTITUTION, showing the number of wrecks upon our coasts annually, must feel how useful it would be, as one means of preventing loss of life and property, to plant at all important fishing and coasting stations and harbours, good barometers, with known characters, in situations accessible to all. As the BOARD OF TRADE has placed no less than 33 (?) valuable instruments in such situations, and as the ROYAL NATIONAL LIFE-BOAT INSTITUTION is about to place numerous others, it is to be hoped that ere long every part of the coast where they would prove useful will be provided with them.