SCOTLAND. The business proceedings of the British Association were brought

to a close on Wednesday, and the pleasure excursions finished on Thursday. On the whole, the meeting-has been of that equable character which does not raise it above the average. The pleasure-trips have included Lochlomond and the isle of Arran. There have been two converse- =mi. At the evening meetings Dr. Carpenter delivered a lecture on "the Character of Species," and Colonel Rawlinson.on the antiquities of Baby- lon and Assyria. The annual dinner took place on Tuesday. The Duke of Argyll occupied the chair, and the guests- were the elite of the Associa- tion : the Countess Campello, Lady Lyell, Sir Charles Lyell, Sir Rode- rick Muechisoh, Colonel Sabine, Colonel Rawlinson, Dr. Shaw, Mr. Robert Chambers, Mr. Monckton Milnes, Professor Sedgwick, Prince Lu- cien Bonaparte, Professor Nicol, and Sir John Richardson, figure-fir the list of names. The speaking after dinner did not rise above a strain of elegant compliment and reciprocal good feeling. The Duke of Argylre brief address, in proposing " the University of Cambridge and Professor Sedgwick " is a specimen of the pleasant things the savants found to say of each other.

'I have now to propose the University of Cambridge and Professor Sedg- wick. On one side of me I see Sir Roderick Murchison, the famous geolo. gist, who has taken possession of a part of Wales- ancl made it his own, under the name of Siluria. He is also famous in Russia, part of which he has appropriated. And, gentlemen, he was born on the East coast of Scot- land; being, as he himself observed in one of the Sections, nothing more than a fish from the old red sandstone. (Laughter and cheers.) We have also here another name distinguished in sciencer that of Mr. Hugh Miller. On. my other hand there is Sir Charles Lyell, who has an extensive range-of scientific- acquirement& he also is a Scotehman. I was long puzzled to know why my countrymen have studied the science of geology so earnestly, but a circumstance recently occurred which in a great measure explains. it. One day as I was walking in. Edinburgh, I observed two boys- with their satchels- on their backs, ' trudging along unwillingly to school' : just as they came in front of the Castle rock, one of them said to the other, • Ay, man, I wonder boo that castle was built '—he seemed to be an amateur geologist of the same class as my friend Professor Sedgwick : the other, who seemed to be more like my friend Sir Charles Lyell, replied, ' May be it growed dare say in him Sir Charles will recognize a young disciple. I proceed now to ask you to drink to 'The health of Professor Sedgwiek,' who is one of the most distinguished men connected with geology. We honour hira for his great attainments, and for the genial manner which distinguishes him; and with him we couple that college of which he is an eminent professor—the University of Cambridge." (Great cheering.)

At a meeting of the General Committee, on Tuesday, after an.animated discussion, it was determined that Cheltenham should be the rallying- point for the Association next year. Dr. Daubeny was elected President, and the Earl of Dade and the Bishop of Gloucester Vice-Presidents.

Some extracts from papers read in the Sections on subjects of genera interest may not be unacceptable. Dr. Scoresby addressed the section of Mathematical and Physical Science on the magnetism of iron ships and its changes ; laying down and elucidating these propositions-

" That the spontaneous influence of simple induction is to develop in the fabric of an iron ship, whilst on the stocks, a magnetic condition, having a. polar axis and equatorial plane conformable to those of the earth ; and that the effect of the mechanical violence to which the material of the ship is. subjected in the process ef building, is to augment the spontaneoua develop- ment into a high degree of intensity of retentive magnetism, with cor- responding polar direction. Thus, if in the interior of an iron ship, at' te place somewhere near the general centre of gravity of the whole of the me- tallic material, we could place a dipping-needle, such needle, supposingit to assume its true position, would point out the direction of the polar axis, or axis of greatest magnetic intensity of the ship ; whilst a plane, as- sumed to extend from the middle or centre of the dipping-needle, at: right angles to the needle's direction, would press through the ship's. aides, 8te., at the place where the iron was magnetically neutral The magnetic polar axis and equatorial plane, originally resulting from the position of the ship whilst being built, are liable to change, and generally do change, after the ship i launched A third fundamental proposition in naval magnetics claiming some elucidation is, that the tendency of mechanical aotion, whilst a ship, in her com- mercial progress, is cast on almost every variety of course, is to reduce the

original obliquity of the polar axis into a vertical or normal position An iron ship's original deviation decreases with time—or rather according to the quantity of service the ship performs, or knocking about she expe- riences. Hence the further fact of experience that in readjustments of the compass, the magnets designed to act antagonistically to the ship's deviating. action require to be removed further off. And, finally, we find that other result of experience—that the compass action in iron ships improves in satis- factoriness with their progress in sea-going service, so as, in a large number of cases, to give little trouble or anxiety to the navigator After the attainment of the normal position of the ship's magnetio axis, such normal. position is liable to be disturbed, transiently or temporarily, by violent

shocks of the sea, or very heavy straining, especially on changes of course after long sailing in one direction." Dr. Scoresby denies that the practical difficulty of correcting compasses of iron ships is overcome. "Now, let it be

observed, that iron ships are incapable of correct compass-guidance ; for it is the ultimate aim of all my discussions and inquiries on the subject to show that the liability to compass-disturbances may be satisfactorily over- come, but that the compasses as ordinarily in use, and compasses adjusted by fixed magnets, cannot be safely relied on. In particular ships, experience may show that the various magnetic pieces about the deck are mutually com- pensating; and with a very large proportion it may not be improbable the compasses are found to act sufficiently well for general utility and safe guid-

ance. But nevertheless, I must affirm, supported by the accordance of mag- netic experiments and sound magnetic principles, and a large body of posi- tive evidence in the form of facts of experience, that the magnetic polarity

is liable to shift in any iron ship, and that such change may produce, and almost always does, compass-disturbance—not a. disturbance always so con-

siderable as to be practically appreciable or endangering, but yet strictly and truly tending to interfere with the true or previously imagined normal condition of experience."

In the section of Mechanical Science, Mr. Ward, in the absence of Mr. Bridges Adams, read a paper on Artillery and Projectiles.

The object of this paper was to call attention to the great importance of the length of bore in artillery, in proportion to diameter, and the desirability of increasing length rather than diameter, with a view to increased range. The length of ancient artillery, of Eastern artillery, and that of rude nations gene- rally, and in modern times the length of American rifles, and also of ducking guns, was adduced as collateral proof. The fact that longpieces of artillery are more difficult to construct than short ones, and especially by nations with rude appliances, makes it very probable that some great gain is the result of length, or the rude nations would have abandoned it for the sake of facile construction. The apparent advantages to be gained by length were—first, greater certainty of aim ; secondly, greater truth of direction ; thirdly, ex- pansive action of the powder in addition to the mere explosive force, follow- ing up the projectile, instead of being wasted on the atmosphere ;the great weight of material affording by its inertia a better abutment for the powder to act on the shot, and a greater security against vibration, as evidenced by the lessened recoil of a heavy gun as compared with alight one. and it was argued that without some such advantages an American hunter would not carry into the woods so long and heavy ? rifle. Reasoning by analogy, if the American rifle were right, modern artillery was wrong. Probably. the in- feriority of ancient powder in its explosive effect, i. e. its slow burning, had given rise to the length of guns at the outset ; and the fact that modern gun-cotton was judged unfitted for hand-guns and artillery, though the

best material for blasting rooks, was an indication that expansive action was an important element as applied to projectiles, lessening the sud- den strain on the gun without losing effect. Modern artillery has been shortened for inconvenience of weight in transport, and to save space on shipboard ; and it had been sought to compensate for the lost advantages by increasing the strength and quantity of the powder. Another object in this paper was to point out the necessity for breech-loading as an accompaniment of long guns. It was shown that the inefficiency of breech-loading hitherto had been caused by the brittle nature of the material—cut iron, by the want of sufficient increase in the quantity of material to compensate for the loss of contiguity, and by the imperfect practice of making the transverse open- ing of an angular form, instead of a curved form. The breech-plug should be of circular or oval section, with a simple wedge-arrangement to move it in and out of position, and with the vent passing horizontally through it to the powder, thus saving the gun from damage, and replacing a worn vent with a new breech-plug. In steam-vessels, streams of water could be driven through breech-loading guns to cool them down when heated. The prin- ciple of charging the gun was dwelt on ; and it was considered as a steam- engine cylinder, the steam being provided by the combustion of the powder, instead of by a separate boiler. The necessity was pointed out of having the bore smooth and polished and free from rust, and also the importance of using a separate steam-piston of wad to stop windage, which it was essen- tial should be elastic and lubricated; showing also that making a non-elastic projectile serve as a piston or wad to stop windage was a very unmechanical process. In charging a breech-loading gun, a strong, thick, well-tallowed wad of papier rnache should be placed behind the powder, which would effectually close the joint. In front of the powder should be a cylindric piston of papier mache, also tallowed, formed of a salient and reentrant cone, one entering the other, and spreading out so as effectually to close the windage ; the total length of the cylinder piston being in excess of the diameter of the bore, and acting elastically on the projectile, to prevent frac- ture. A new form of projectile was advocated—a bayonet-section, with the centre or core thicker towards the point to put the centre of gravity in ad- vance of the central length, and keep it point foremost. This would give greater power of penetration, a maximum of resistance area, and greater ac- curacy of flight, with increased range, in the principle of the long and nar-

row steam-boat through the water. The edges or feathers of the projectile to fit accurately the bore of the gun, and to be formed either parallel or with a rifle-spiral ; but the rifle principle was considered in all eases to diminish

range, by absorbing power in guidance. A rocket might be formed on the same principle, taking up a secondary self-projecting power after the ex- penditure of the first. A new kind of trunnion was advocated—a spherical ring formed in the gun, and acting as a ball and socket, so that by means of a slot-sight the gun might be used with a closed port ; the recoil being ab- sorbed by caoutchouc, and the gunner's breech-loading would be perfectly

protected. Allusion was made to a proposition of General Bentham to fix guns in steam-vessels, and aim them by steam and rudder power. The writer proposed to fix very heavy long guns at a determined angle length-

long with the keel, on the breech-loading plan, and to attain the range by advancing or retreating. After alluding to the defective strength and in- ternal crushing of cast-iron guns, the writer argued on the desirability of lining them with malleable metal to stop the pores; and set forth a new plan for forging wrought-iron guns, by preparing short cylinders accurately

turned to jet each other, heating them by radial jets of gas under compres- sion like a large blow-pipe, and producing welded joints by hydrostatic com- pression of the cylinders one on the other ; thus avoiding all percussion and overheating, and producing a fibrous instead of a granular mass, with the fibres round the axis of the gun.

In the section of Chemistry, Professor Ramsay of Glasgow described a process by which Mr. Robert M'Pherson, of Rome, bad succeeded in ob-

taining beautiful photo-lithographs ; specimens of which had been hung up in the photographic exhibition now open in connexion with the .Asso- elation. The steps of the process are as follows- " 1. Bitumen is dissolved in sulphuric ether, and the solution is poured on an ordinary lithographic stone. The ether quickly evaporates, and leaves a thin coating of bitumen spread uniformly over the stone. This coating is sensitive to light; a discovery made originally by M. Niepre, of Chalons. 2. A negative on glass, or waxed paper, is applied to the sensitive coating of bitumen, and exposed to the full rays of the sun for a period longer or shorter according to the intensity of the light ; and a faint impression on the bitu- men is thus obtained. 3. The atone is now placed in a bath of sulphuric -ether, which almost instantaneously dissolves the bitumen, which has not been acted upon by light,- leaving a delicate picture on the stone, composed of bitumen on which the light has fallen. 4. The stone, after being carefully washed, may be at once placed in the hands of the lithographer ; who is to treat it in the ordinary manner with gum and acid, after which proofs may be thrown off by the usual process." Professor Ramsay stated, that this process, modified, had been employed with success to etch plates of steel or copper, without the use of the burin. " 1. The metal plate is prepared with a coating of bitumen precisely in the manner noticed above. 2. A positive picture on glass or paper is then ap- plied to the bitumen, and an impression is obtained by exposure to light. 3. The plate is plunged into a bath of ether, and the bitumen not acted upon by light is dissolved out. A beautiful negative remains on the plate. 4. The plate is now to be plunged in a galvano-plastic bath, and gilded. The gold adheres to the bare metal that refuses to attach itself to the bitumen. 5. The bitumen is now removed entirely by the action of spirits and gentle heat. The lines of the negative picture are now represented in bare steel or copper, the rest of the plate being covered by a coating of gold. 6. Nitric acid is now applied as in the common etching process. The acid attacks the lines of the picture formed by the bare metal, but will not bite into the gilded surface. A perfect etching is thus obtained."

Among the papers read in the Geographical Section, was one describ- ing the results of a scientific expedition to Babylon, by Dr. Julius Op pert. A few extracts may prove interesting.

"Observing the startling fact of the same size and grandeur of all Baby- lonian square bricks on one side to be of the identic size of all stone slabs on the other, I measured 550 bricks and all the stone slabs I could find, with the utmost accuracy; and I found then that the side of the brick square was to the side of the stone square like three to five ; that the former of an amount 0.m. 315 was the Babylonian foot, while the latter was the Baby- lonian cubit, and 0.m. 525 long ; and by a surprising but not fortuitous co- incidence, this value of Om. 525 is exactly the length of the Egyptian cubit. I found that the Chaldeans had a greater measure of 360 cubits—viz. 600 feet; and this greater itinerary length was the stadium of the Chaldeans of 189 m., only fourteen feet longer than the Olympic one. As Nebuchadnez- zar and Herodotus assign both the circuit of the walla of Babylon a length of 480 stadia, the square side of 120 will be 22,680 metres (fourteen miles) ; and my trigonometrical survey has proved the truth of my reasoning Babylon thus filled a space of 513 square kilometres—viz. a little more than 200 square miles. But this huge surface was not all inhabited : in the exte- rior enclosure, made by Nebuchadnezzar, were contained immense fields, that in case of siege provided the city with corn and protected her from the horrors of famine. This exterior wall is said to have been destroyed by Da- rius when he took Babylon. But there were in the inside of that great eir- cumvallation five other walls, as the most important of the Babylonian writers assures us, and this statement is confirmed by the Babylonian in- scriptions. The next concentric circumvallation, which we may name C., was a square in the same direction as the exterior, but only of 360 stadia (ten miles a side). Concentric with this wall was a third, that enclosed the real city of the Babylonians, situated at the very spot of the town of Hillah