February 29, 19 12] 



NATURE 



595 



tory on the east and a base terminal point on the west 

 of the valley by a method especially suitable to the case, 

 and the reobservation of the azimuth of the southern side, 

 the conclusion is reached that in this part of the Nile 

 Valley the local attraction in the prime vertical is 8-8" 

 and 6-9" by different methods on the northern side, and 

 12-6" on the more southern side, the plumb-bob being re- 

 pelled from the axis of the Nile Valley. The method 

 employed is described. 



We have received the fourth and concluding part of the 

 first volume of the Bulletin of the Seismological Society 

 of America. The papers which it contains are mostly 

 brief. Among the more interesting may be mentioned a 

 biographical notice with an excellent portrait of Major 

 C. E. Dutton, described, in forgetfulness of Prof. C. G. 

 Rockwood, as America's first seismologist. Mr. Otto 

 Klotz gives a simple method of locating the epicentre of 

 an earthquake from the duration of the first series of 

 tremors at three widely separated stations. Mr. E. C. 

 Templeton describes a rather strong earthquake on July i, 

 iqii, in Central California. From the nature of the 

 shock and the disposition of the isoseismal lines it is 

 evident that the earthquake was a twin, the more important 

 of the two foci being situated near Coyote, a village twelve 

 miles south-east of San Juan. The paper of greatest value 

 IS one by Prof. A. C. Lawson on a remarkable series of 

 small post-Glacial fault scarps near Banning, in western 

 Ontario. They have been exposed by the removal of the 

 ■glacial drift, which until recently has helped to preserve 

 the sharpness of the scarps. The glaciated rock so far 

 uncovered is about a quarter of an acre in area, and is 

 dislocated by a large number of small reversed, or over- 

 thrust, faults. Along a transverse line 66 feet in length 

 twenty-four scarps were counted, the height of which 

 ranges from an eighth of an inch to 3J inches. The move- 

 ment of the faults, as shown by the displacement of the 

 glacial striae, was invariably in the direction of the dip. 



The Journal of the Franklin Institute for January con- 

 tains a noteworthy paper, recently read by Prof. Cleveland 

 Abbe, entitled " The Obstacles to the Progress of Meteor- 

 ology." To form an adequate idea of the important ques- 

 tions dealt with it would be necessary carefully to peruse 

 the paper. Prof. Abbe states at the outset that he is not 

 a pessimist. He says :— " We have been so long accus- 

 tomed to fairly accurate and very useful daily weather 

 forecasts that we begin to look for perfection in long- 

 range predictions. Let us be optimistic and believe that 

 eventually these will come." But he asks why it is that 

 that progress has been so slow, and why we have been 

 unable definitely to establish the existence of periods in our 

 local climates. Possibly they do not exist, but if they do 

 they are completely covered up by the defects of observa- 

 tions. He gives a number of illustrations showing that 

 observations have been at fault because instruments have 

 been faulty, exposures changed by growth or disappear- 

 ance of trees, and various other causes. Although balloon 

 observations now record what is going on ten or fifteen 

 miles above us, and although daily weather maps have 

 been published for the whole of the northern hemisphere, 

 the great obstacle that hinders perfect prediction is our 

 ignorance of many details as to the laws that govern the 

 atmosphere. The author considers that the existence of 

 laboratories specially adapted to atmospheric experiments 

 is of fundamental importance, and the association there- 

 with of able students trained in mathematics and physics. 

 " When all this is realised, the intellectual work that will 

 there be done will gradually remove all obstacles to the 

 fventual perfection of our knowledge of the atmosphere." 

 But, as in the case of astronomical observatories and all 



other scientific institutes, plans must be made for many 

 years of labour. 



Since the introduction of the earth inductor as an instru- 

 ment for the determination of the magnetic dip, the ques- 

 tion is often asked, Does the earth inductor or the dip 

 circle give the more accurate results? The editor of 

 Terrestrial Magnetism and Atmospheric Electricity gives 

 the results of his experience in a note in the December 

 (191 1) number. The earth inductor, once set up, gives 

 a result in fifteen minutes five times as accurate as the 

 dip circle will give in an hour. W'hWe dip circles differ 

 amongst themselves by a few minutes, inductors agree to 

 within a few tenths of a minute of arc. For survey work, 

 when the instrument has to be set up afresh at each place 

 of observation, the present type of inductor has no 

 advantage over the dip circle, but it is hoped that ere 

 long an inductor suitable for such work will be constructed. 

 The first number of the Science Reports of the T6hoku 

 Imperial University, Sendai, Japan, contains an important 

 paper by Prof. Honda on the thermo-magnetic properties 

 of forty-three chemical elements, most of which were 

 obtained in a state of great purity. The magnetic suscepti- 

 bilities of these elements up to temperatures in many cases 

 exceeding 1000° C. were measured by the pull exerted on 

 them by the non-uniform magnetic field between the pointed 

 poles of a Du Bois electromagnet. The strength of the 

 field could be increased to 23 kilogauss, and was deter- 

 mined by the aid of a small coil and a ballistic galvano- 

 meter. The pull was measured by means of a torsion 

 balance. With the exception of iron, nickel, and cobalt, 

 these elements have susceptibilities which are independent 

 of the intensity of the magnetic field. Some of them 

 change their susceptibility with change from solid to liquid 

 or from one crystalline form to another. The suscepti- 

 bility appears to be connected intimately with the position 

 of the element in the periodic system of chemical classifi- 

 cation. The laws stated by Curie, i.e. for diamagnetic 

 substances, susceptibility generally independent of tempera- 

 ture, and for paramagnetic inversely proportional to the 

 absolute temperature, were found not to be correct, and 

 Prof. Honda substitutes the law : increase of temperature 

 produces a change of susceptibility towards that of the 

 element of next higher atomic weight. 



So.ME interesting conclusions concerning the spectra pro- 

 duced in gases and vapours by different types of electric 

 discharge are recorded by M. G. Millochau in a paper 

 which is published in No. 18, vol. cliii., of the Comptes 

 rendus. By projecting an image of the spark on to a 

 slit, an image of which was in turn projected on to a 

 photographic film revolving at a known rate, the author 

 obtained photographic evidence as to the nature and dura- 

 tion of the discharge. At the same time he photographed 

 the spectrum produced in various gases, enclosed in 

 Plucker tubes, by the different discharges, and so was 

 able to correlate the different spectra with the respective 

 types of discharge producing them. By this means he 

 differentiates seven types of " simple " discharges, each of 

 which always produces the same spectrum, whatever may 

 be the pressure in the tube, and finds that in a complex 

 discharge the resulting spectrum is the summation of the 

 spectra produced by the several superposed " simple " dis- 

 charges ; the simple discharges range from a continuous 

 discharge obtained, for example, by joining up the 

 terminals of the secondary of a Ruhmkorff coil, without 

 condenser, directly to the terminals of the vacuum tube, to 

 an intermittent discharge from a condenser through a 

 considerable resistance. The " simple discharges " may be 

 grouped under three general heads : — (i) the slow dis- 



NO. 2209, VOL. 88] 



