August i, 1907] 



NATURE 



541 



mercury, and the air in tlie chamber is no longer in con- 

 neclion' with the receiver. But as the drum contains three 

 chambers, one of them is always above the mercury ; hence 

 the action is continuous. As the cha.mber revolves W 

 becomes more and more immersed in the mercury, and the 

 air is forced out through the channels Z into the space 

 between ihe drum and cising, from whence it is removed 

 by Ihe auxiliary pump. 



Fig. 3 illustrates the glass attachment, which can be 

 fitted on to the tubes R and R', Fig. 2, by means of 

 the ground pieces I, and L,. The receiver to be exhausted 

 is attached at E. A manometer H, with a drying chamber 

 P filled with phosphorus pentoxide, is employed to measure 

 the pressure. It also serves as an automatic valve; at 

 atmospheric pressure the orifice O is open ; therefore the 

 auxiliary pump connected at S exhausts the receiver fitted 

 at E, directly through the opening O and the connecting 

 tube P. On a vacuum of 20 mm. being attained, the 

 mercury sinks in the right-hand limb, and, rising on the 

 left, closes the opening O as illustrated in the figure ; the 

 mercury pump is then started. 



Figures are supplied showing the extreme vacuum which 

 can be obtained in a few minutes. Thus in five minutes 

 the MacLeod gauge registered only 0027 mm., and after 

 fifteen minutes o-ooooo;5 mm. This shows that the pump 

 works extremely rapidly and very efficiently. If it is 

 capable of doing all that' is claimed for it, the Gaede pump 

 should prove of great value either for research work or for 

 showing lecture experiments with high vacua. 



THE CAUSE OF EARTHQUAKES. 



A MONG the results produced by the San Francisco 

 ■^ earthquake of April iS, 1906, must be reckoned a 

 memoir, by Prof. T. J. J. See, covering 140 pages of the 

 Proceedings of the American Philosophical Society (vol. 

 xlv., October-December, 1906), on the cause of earthquakes, 

 mountain formation, and kindred phenomena. The ex- 

 planation adopted is a development of an old-fashioned 

 idea, and is supported by quotations from the writings of 

 natural philosophers from Aristotle down to Charles 

 Darwin. Earthquakes, with volcanoes and mountain 

 ranges, are all ascribed to the explosive power of steam 

 formed within or just beneath the heated rocks of the 

 earth's crust, chiefly by the leakage of sea water through 

 the ocean beds ; the pressure of this steam forces the lava 

 in a lateral direction, and its subsequent condensation 

 leads to the subsidence of the sea bottom often observed 

 after great earthquakes ; the lava forced aside may either 

 break out through volcanic vents or may lift the overlying 

 rocks into mountain ranges, and, when the movement is 

 sudden, give rise to faults and fractures which are the 

 result, not the cause, of earthquakes. 



It is round these last words, italicised by Prof. See, 

 that criticism naturally centres, and the first consideration 

 which arises is the verbal one of what is an earthquake 

 and what is a cause. An earthquake, as ordinarily under- 

 stood, is a shaking of the earth, and this shaking is due, 

 wholly in the great majority of cases, and very largely in 

 the remainder, to the molecular movements involved in the 

 transmission of elastic wave motion. In the case of great 

 earthquakes, fractures of the solid rock, accompanied by 

 more or less displacement of the opposite sides of the 

 fissure, are often found, and as the shaking of the earth 

 is greatest near these, and the disturbance is propagated 

 outwards from them, they have been regarded as the 

 cause of earthquakes. In other cases, where no actual 

 fissure is observed at the surface, there is good reason to 

 suppose that the earthquake was caused by an underground 

 fracture, which did not reach the surface, and there can 

 be no doubt that this explanation is adequate in almost, 

 if not quite, every case; but even if the fracture is the 

 immediate cause of the disturbance which is commonly 

 known as an earthquake, the explanation is still incom- 

 plete, for we have not reached the cause of the fracture. 



It is to this ultimate cause that Prof. See appears to 

 apply the term earthquake, and he is probably right in 

 rejecting the tectonic hypothesis either in the form in 

 which it presents itself to him or in the more ordinary 



NO. 1970. VOT. 76I 



one which regards the fractures as the result of com- 

 pressional strains, largely due to the secular contraction of 

 the earth, but his explanation fails to account for the re- 

 markable' connection between the irregular shifting of the 

 earth's axis and the occurrence of great earthquakes. 

 That these irregular movements of the axis are greatest 

 when large earthquakes are tnost frequent is a certain, 

 but as yet unexplained, fact ; it seems to necessitate dis- 

 placements of matter in the earth on a far larger scale 

 than is indicated bv the differential measurements which 

 alone are open to ' us. Prof. See's explanation, though 

 it provides for lateral and vertical displacements of matter, 

 necessitates the elevations and depressions being so closely 

 contiguous as practically to neutralise each other's effects, 

 and, therefore, fails as an explanation of the ultimate cause 

 of earthquakes, while it in no way affects the current 

 acceptance of fracture as their immediate cause. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Leeds.— The retirement of Prof. Miall, F.R.S., from 

 the chair of biology, which he has occupied in the York- 

 shire College, and subsequently in the University of 

 Leeds, since the year 1876, was recently made the occasion 

 for expressing iii a tangible way the esteem and regard 

 in which he is held by his colleagues and friends. A 

 testimonial committee, of which the Vice-Chancellor (Dr. 

 Bodington) was chairman, was formed, and a ready re- 

 sponse was obtained to the circular inviting subscriptions 

 for this purpose. Among the testimonials to Prof. Miall 

 which have been thus provided is a portrait by Mr. 

 Frederick Yates, intended to be hung in the hall of the 

 University. The presentation of this portrait was made 

 at a recent meeting in the University library, when a 

 large number of his colleagues and friends were present. 

 The Vice-Chancellor, who presided and made the present- 

 ation, spoke in warm and feeling terms of the eminent 

 services which Prof. Miall had rendered to the college 

 and University, as well as to the cause of science, and 

 described him as having been original as a teacher, eminent 

 as a scientific w^orker, and active as a business colleague. 

 Subsequent speakers included Mr. S. P. Unwin, Dr. 

 Eddison (emeritus professor of the University), and Prof. 

 Smithells. Prof. Miall, in acknowledging the presentation, 

 gave a short historical sketch of the -foundation of the 

 Yorkshire College of Science and its development into the 

 Yorkshire College and subsequently into the University 

 of Leeds. 



The chair of biology will in future be divided into the 

 professorships of zoology and of botany. To the former 

 has been appointed Dr." Walter Garstang. Prof. Garstang 

 has held research fellowships in zoology at Owens College, 

 Manchester, and subsequently at Lincoln College, Oxford, 

 where he has filled various appointments as lecturer 

 and examiner. He is at present chief naturalist to the 

 Marine Biological .Association in charge of the Lowestoft 

 Laboratory. 



To the chair of botany Mr. V. H. Blackman has been 

 appointed. Prof. Blackman was sometime fellow of St. 

 Tohn's College: he has held an assistantship in the British 

 Museum, having charge of the collection of fungi, and he 

 is at present engaged in botanical teaching, being a recog- 

 nised teacher of that subject in the University of London. 



In connection with the new department of fuel and 

 metallurgy under Prof. Bone, F.R.S.. the Institute of Gas 

 Engineers has established a research fellowship of the value 

 of loo^ a year. 



The extensions of the University buildings upon which 

 the council is at present engaged comprise :— (1) an 

 extension of the main building in College Road for^ the 

 better accommodation of biology and of arts teaching ; 

 (2) an extension of the civil and mechanical engineering 

 department ; (3) the erection of a detached block for the 

 department of electrical engineering ; (4) an extension of 

 the cloth finishing department ; (~,) the completion of the 

 block of buildings for the mining and metallurgical depart- 

 ments. The last-mentioned block will be ready for occupa- 

 tion by the students at the beginning of next session, in 

 October. In addition to these buildings, the University is 



