May 12, 1887] 



NATURE 



37. 



weights and by means of metallic or air springs. In the 

 former case it is easy to see how the counterweight can 

 be so arranged that the work represented by the falling of 

 the gun may be exactly balanced by the work of lifting 

 the balance weight; the energy of recoil, therefore, need 

 only be drawn upon to overcome the friction of the 

 descent and the subsequent friction of ascent, together 

 with the accelerating force necessary to start the gun into 

 smart upward movement. The total amount of work 

 expended in friction does not probably exceed 20 per 

 cent, of the work of raising the gun, and consequently 

 the old muzzle-loaders, with their comparatively small 

 charges and low muzzle velocities of projectile, yield 

 ample power to allow the guns to be lowered completely 

 beyond the reach of hostile shot. 



This is a consideration of great importance, because 

 year by year a large number of excellent muzzle-loading 

 guns of all calibres will be returned into store from the 

 Navy, and may at once be utilised for strengthening our 

 coast defences, for they are quite powerful enough to act 

 against unarmoured vessels, light-draught transports, and 

 such like, as well as against the unprotected parts of 

 ironclads ; while as howitzers they would be invaluable 

 for preventing landing from boats, and for this service 

 would be quite as effective as the longer, more costly, 

 and more delicately-made breech-loaders, which, however, 

 should be associated with them to resist ironclads. It so 

 happens, also, that the short muzzle-loader is particularly 

 well suited to the Moncrieff carriage, because the men 

 engaged in loading, training, and elevating, working com- 

 pletely under the parapet, are in absolute safety from the 

 enemy's fire, and the only man exposed is he who lays the 

 gun, and even that exposure, as we have already remarked, 

 can often be dispensed with. The muzzle-loaders are also 

 much more simple weapons to manage than the modern, 

 more powerful guns, and would therefore be better fitted 

 for coast batteries, which would undoubtedly have to be 

 manned and worked by Volunteers and men not so highly 

 trained as the Artillery of the regular army. 



Some years ago, the War Office definitely adopted the 

 Moncrieff counterweight carriage, and mounted, success- 

 fully, guns as large as the 9-inch of 12 tons weight ; but 

 after a time evil counsels prevailed, inveterate prejudice 

 triumphed, and the nation has been saddled with a vast 

 expenditure on forts, which are already obsolete, for by 

 no sort of ingenuity can they be made to carry artillery 

 fitted to cope with that which will be opposed to them. 

 Not that the system was ever rightly applied : Colonel 

 Moncrieff, though attached to the War Department for 

 the express purpose of developing his views, does not 

 appear to have been consulted as to the arrangement of 

 his batteries, or, if consulted, his views were ignored, and 

 the consequence is that, in the case of the comparatively 

 few guns which have been mounted, most of the em- 

 placements are made as conspicuous as possible, and in 

 that way the inestimable advantages of concealment have 

 been thrown away. 



The counterweight system, however, becomes very 

 cumbersome when guns exceed some 20 tons in weight. 

 Recourse can then be had to compressed air as a means of 

 storing the energy of recoil. But the work done in com- 

 pressing air reveals itself in the form of heat, which raises 

 its temperature, and is slowly dissipated as it cools. 

 Again, the air, in expanding to raise the gun, is cooled 

 by the amount of heat converted into work, and its 

 pressure is thereby reduced, so that the losses on these 

 two accounts, added to the somewhat increased friction 

 of the machinery, set a limit to the height to which the 

 stored energy of recoil can raise the gun : the increased 

 charges used in modern artillery, however, compensate 

 for these losses, and it is possible by hydro-pneumatic 

 arrangement to give efficient cover to the heaviest guns. 

 The natural fear arises lest the introduction of water 

 and compressed air may not add elements of danger in 



the facility with which dirt and debris, not sufficient to 

 injure an ordinary mounting, may affect the more com- 

 plicated arrangement. There is no doubt that a breech- 

 loading gun requires more care in its use than a muzzle- 

 loader, and a hydro-pneumatic mounting is not so simple 

 as a carriage with an ordinary friction or hydraulic 

 compressor, but experience with the 6-inch hydro- 

 pneumatic siege carriage has shown that the system 

 is capable of enduring very rough usage, and is by no 

 means easily deranged. 



The Australian colonies, acting under the advice of 

 the late General Scratchley and General Steward, seem 

 to be more intelligent and far-seeing than the mother 

 country, and have acquired a considerable number of 

 breech-loading guns, mounted on the system recom- 

 mended, and carried out completely in all its details. 

 It is difficult to see how official opposition can long brave 

 the assaults made on it by common-sense, and the 

 glaring defects of the old methods. 



{To be continued.) 



THE TEMPERATURE OF THE CLYDE 



SEA-AREA. 



I, 



IN the spring of 1886 a regular system of temperature 

 observations was commenced in the water of the Clyde 

 sea-area, by the staff of the Scottish Marine Station, under 

 the personal superintendence of Mr. John Murray of the 

 Challenger Commission. The work has since proceeded 

 steadily, and will probably be continued to the close of the 

 present year. Previous to 1 886, few temperature observa- 

 tions had been recorded dealing with the deep water on 

 the west coast of Scotland ; these were almost entirely the 

 work of Mr. J. Y. Buchanan on occasional summer cruises. 



The scope of the present investigation is limited chiefly by 

 the capabilities of the Marine Station's steam-yacht i^,?^«ja. 

 She is a vessel of 30 tons, yacht measurement, steaming 

 6 knots in ordinary circumstances ; but not adapted for 

 working amongst the tremendous tidal currents of the 

 North Channel except in the calmest weather. On the 

 other hand, her small size, and the convenient arrangement 

 of a steam-winch for working the sounding-line enables 

 observations to be made with great rapidity in quiet water. 

 Inside of Cantyre, soundings have been obtained in almost 

 every kind of weather, and the present article will deal 

 with this part of the west coast only. 



The Clyde sea-area 1 comprises all the connected water- 

 system, 1300 square miles in extent, lying to the north of 

 a line drawn from the Mull of Cantyre to Corsewall Point 

 in Wigtownshire. This line corresponds nearly to the 

 50-fathom contour ; outside it the depth increases rapidly 

 to over 80 fathoms ; towards the inner or northern side it 

 diminishes at first, and then remains at about 27 fathorns 

 over an area of 270 square miles. This bank is 

 termed the Clyde Barrier Plateau ; it crosses from 

 Cantyre to Ayrshire, past the south end of Arran, and 

 around Ailsa Craig. The shallowest water covers a 

 ridge at a depth of about 20 fathoms from the surface. 

 The water deepens on the inside of the Plateau to 

 form the Arran Basin, which in form resembles the 

 letter X, surrounding Arran on the west, east, and north, 

 and running up into Lower Loch Fyne. The depth in 

 this basin exceeds 50 fathoms over 100 square miles ; the 

 deepest water, 107 fathoms, occurs off Skate Island, near 

 Tarbert. A much smaller depression runs in a straight 

 line from the Cumbraes to Dog Rock at the mouth of 

 Loch Goil. It is known as the Dunoon Basin, and has 

 an average depth of 40 fathoms and a maximum of 56. 

 Of the numerous lochs, reference will be made to two only, 

 Upper Loch Fyne and Loch Goil. The former measures 

 25 miles from Otter Ferry to the head ; it consists of a 

 basin 30 fathoms deep, bounded by channels having an 



' For detailed description and map see Scottish Geographical Magazine 

 for January 1887. 



