NA TURE 



[Jan. 15, i : 



awaiting investigation is whether any perceptible effect on 

 the height and form of a mountain chain can be detected 

 after its flanks have been convulsed with earthquakes ; 

 whether its rocks have been more tilted or folded or frac- 

 tured. Men are usually too overwhelmed by the losses to 

 life and property to take heed of such matters as these, 

 and it may seem almost cold-blooded to suggest them for 

 practical consideration. In all mountain districts much 

 subject to earthquakes, it would be desirable to have an 

 accurate system of levelling carried out, so that after a 

 time of disturbance the heights could be checked. It 

 would also be useful to have numerous photographs of 

 cliffs and other sections where the rocks are well exposed, 

 and where, therefore, any change of inclination, even to 

 a slight extent, could be ascertained and measured. In 

 regions where, as in the Karst, the earthquakes probably 

 arise from the giving way of the roofs of underground 

 tunnels or caverns, likewise in volcanic districts, the 

 precautions here suggested might be of little use. But 

 in those tracts where mountain-making is probably still in 

 progress, they might supply us with many suggestive facts. 



There is one other feature in the present Andalusian 

 earthquakes to which allusion should be made. It has 

 often been asserted and often denied that the occurrence 

 of earthquakes is connected with the state of the atmo- 

 sphere at the time. There certainly seems no doubt that 

 in Europe, at least, the crust of the earth is considerably 

 more convulsed by earthquakes in winter than in summer. 

 When the shock of December 25th struck terror into the 

 provinces of Malaga and Granada, the barometer, which 

 a fortnight before had been remarkably steady, was ex- 

 ceptionally low and variable. Mr. George Higgin, of 

 Broadway Chambers, Westminster, sends us an extract 

 from a letter received by him from one of his engineers 

 at Albox, in the valley of the River Almanzora, province 

 of Almeria, not far to the eastward of the scene of 

 disturbance. The writer, who was still unaware that 

 there had been any earthquake, states that after Decem- 

 ber 19th a severe gale sprang up, lasting four days ; the 

 barometer varied from 29/2S on December 19th to 28'52 on 

 the 27th, and continued to oscillate to such an extent that 

 no trustworthy levellings could be made with it. A cor- 

 respondent of the Times, writing on Sunday last, also 

 mentions the low state of the barometer, and that the 

 severest and greatest number of shocks continues to be 

 felt from 5 p.m. till 5 a.m., and that since the outset, at 

 intervals of about a week, the movement has shown a 

 recrudescence with each return. 



There has been also the usual chronicle of secondary 

 effects from the earthquake shocks. Landslips have 

 occurred, with the consequent disturbance of drainage. 

 In one place a village has slid northwards about sixty feet, 

 leaving a deep semicircular crevasse where it previously 

 stood. The displaced ground has intercepted the course 

 of an adjacent stream, so that a lake is forming behind the 

 obstruction. At Periana a mass of rock and earth, disen- 

 gaged from the slopes above, is said to have demolished 

 a church and 750 houses. Among the numerous sulphur- 

 springs of the region there has been considerable disturb- 

 ance. Some of these sources, as has often been observed 

 at Vesuvius and elsewhere, disappeared after the first 

 shock, but in a day or two afterwards began to flow again 

 at a higher temperature than before. 



THE STABILITY OF SHIPS 

 A Treatise on the Stability of Ships. By Sir E. J. Reed, 

 K.C.B., F.R.S., M.P. (London: C. Griffin and Co., 

 iSSO 



THE stability of ships is a subject that has attracted 

 considerable attention of late. Many disasters have 

 happened to ships through insufficient stability, and have 

 caused scientific men as well as practical naval architects 

 to apply themselves to a renewed and close investigation 

 of the subject. The result is that the ideas which till late 

 prevailed respecting it are seen to be often superficial and 

 incomplete, and in some cases not entirely free from 

 error. 



Sir Edward Reed has done good service in bringing out 

 a treatise upon stability which presents the matter in a 

 fresh, readable, and instructive form. Singularly enough 

 this is the only work in the English language which 

 attempts to deal exhaustively with it. Notwithstanding 

 the magnitude and complexity of the subject, and its vast 

 importance to all who are responsible for the wise design 

 and safe management of ships, its treatment has previously 

 been of a very restricted and imperfect character. The 

 student of naval science has required to consult works 

 which range over the wide field of naval architecture, and 

 numerous papers that lie entombed in the published pro- 

 ceedings of learned societies, in order to acquire anything 

 approaching a comprehensive knowledge of the problem 

 of stability. Sir Edward Reed has brought together and 

 placed into relation to each other the investigations 

 made at various times by eminent men of the science of 

 the subject, and the practical developments which have re- 

 sulted therefrom. Among these are included the researches 

 of French mathematicians and naval constructors, which 

 have hitherto been but little known in this country. 



The statement that a floating body, such as a ship, when 

 laden so as to float at a given draught of water may 

 assume any position — upright, inclined, or upside down — 

 or it may when floating upright and in equilibrium be 

 capsized with ease or with difficulty, according to the 

 character or degree of the stability it may possess is the 

 veriest scientific truism. Many may suppose it to be 

 unnecessary, in this shipbuilding country, to make so self- 

 evident an observation. Yet trite and obvious as it mav 

 appear when put into this form, it has been strangely, 

 almost culpably, ignored by many who are responsible 

 for the safety of ships. Very few exact investigations of 

 the stability of individual ships have been made till quite 

 recently ; and even those that were attempted have fre- 

 quently been imperfect and inconclusive. 



The correct principles upon which the stability of ships 

 depends were not demonstrated till the middle of the last 

 century. Bouguer explained the properties of the meta- 

 centre in 1746, and gave a formula by which its position 

 may be calculated. He also showed how the initial 

 stiffness, and height of centre of gravity, of a ship may- 

 be determined by a practical experiment ; this being the 

 method of inclining vessels which is at length becoming 

 usual in this country. Bouguer's investigations were fol- 

 lowed up and extended by D. Bernouilli and Euler ; and it 

 was shown how the righting moments at large angles of 

 inclination from the upright may be determined. 



Atwood brought forward the subject clearly and forcibly 



