August 25, 1892] 



NATURE 



401 



uncertain, but where the observations were referred to it was 

 found that "the two spots with the highest relative temperature 

 were very near the sun's edge." He further suggests that if 

 further observation should establish this fact, viz., that spots 

 "•uffer less absorption than the neighbouring photosphere, we 

 ^rnight consider them " to be in a higher stratum than the 

 'photosphere." 



Hydrogen Spectrum in the Solar Atmosphere.— 

 M. Deslandres, in the Comptes Rendus for July 25, communi- 

 cates a brief note concerning the spectrum of hydrogen that was 

 photographed by him in a prominence on the 4th of May last. 

 This spectrum, besides containing many metallic lines, shows 

 also ten ultva violet radiations of hydrogen and five other new 

 ones, the latter of which, as he says, follow so regularly the 

 former series that one is led to consider them as due to 

 hydrogen. It may be remembered that Mr. Balmer in- 

 dicated a simple function of whole numbers which represented 

 exactly the series of 14 radiations of hydrogen. This 

 function, which is applicable to most of the metals, is 



N = A „ where N is the number of vibrations, A and B 



w- 

 two constants, and « a whole number. In the following table 

 we give the result of M. Deslandres' measures with regard to 

 the new addition to this series, to show how close an agreement 

 exists between the calculated and observed values : — 



Whole Nos. 

 of the 

 formula n. 

 12 

 13 

 14 

 15 

 16 

 17 

 18 

 19 

 20 

 21 



No, of vibrations 



Deslandres. Ames. Calculated. 



266-565 ... 266-575 ... 266-566 



296-685 ... 267-715 ... 267-694 



268-585 ... 268615 ... 268-586 



269-310 ... 269-330 ... 269-309 



269-890 ... — ... 269-898 



270-385 ... — ... 270387 



270-795 ••• — •• 270-797 



271-140 ... — ... 271-142 



271-460 ... — ... 271-448 



271-700 ... — ... 271-694 



Refraction in Micrometric and Photographic 

 Measures. — A very simple method by which the effect of 

 differential refraction may be eliminated from the results of 

 micrometric observations or from the measures of photographic 

 plates is given by Dr. S. C. Chandler in the Astronomical 

 Journal, No. 271, The principle underlying this method is the 

 position of the plate about to be measured, which here is 

 inclined at a certain angle in the vertical direction to the focal 

 plane of the telescope. In the measurement of distances this 

 inclination necessitates the application of a small correction, 

 but this is soon accomplished by the aid of a simple formula, 

 which can be considerably modified by determining the screw 

 revolution directly from the plate. One might at first think 

 that by this means the stellar images would be slightly affected, 

 but Dr. Chandler informs us that he thinks that "attentive 

 examination will show that the difference of definition will be 

 inappreciable." 



THE RECENT EARTHQUAKES. 

 'T'HE first of the earthquake shocks felt on the i8th inst. in 

 -*■ Ireland, Wales, and the West of England was evidently 

 one of unusual strength for this country, and it is very desirable 

 that both it and the subsequent slighter shocks should be tho- 

 roughly investigated, with a view to discovering their origin and 

 their relations to one another. As I have been engaged for 

 several years in working at our British earthquakes, and am now 

 occupied in studying these recent shocks, I should be greatly 

 obliged if you would allow me to ask your readers who felt the 

 shocks for assistance in obtaining the necessary materials. 



It would be of great service to know simply the names of as 

 many places as possible where one or more of the shocks were 

 felt and the accompanying sounds heard. With this knowledge 

 the boundaries of the disturbed area and the sound-area of each 

 shock may be determined — points of considerable importance. 

 But for a complete study of the shock it is desirable to have 

 further details, such as would be given by answers to the ques- 

 tions printed below, especially to those numbered 3, 4, 6, and 7. 

 I shall be most glad and thankful to receive accounts of the 

 earthquakes from any place whatever, and I may add that no 

 account, however scanty the information given, can fail to 



NO. I 191, VOL. 46] 



possess some value or to help in throwing light on the nature 

 and origin of the shock. 



(Note. — If more than one shock was felt it is important that 

 the notes relating to each should be kept separate.) 



(1) Name of place where the shock was felt. 



(2) Situation of the observer : (a) Whether indoors (and on 

 which floor of the house) or in open air : {b) How occupied at 

 the moment of the shock. 



(3) Time at which the shock was felt, if possible, to the 

 nearest minute. 



(4) Nature of the shock, description of the : (a) The number 

 of vibrations : ib) Their relative intensity : {c) Whether there 

 was any tremulous motion before or after the principal vibra- 

 tions : (d) Whether any vertical motion was perceptible, and if 

 so, whether the movement was first upward and then downward, 

 or first downward and then upward. 



(5) Duration of the shock in seconds, not including that of the 

 accompanying sound. 



(6) Intensity of shock : Was it strong enough (a) to make 

 windows, doors, fire-irons, &c., rattle : (1^) To cause the chair 

 or bed on which the observer was resting to be perceptibly 

 raised or moved : (r) To make chandeliers, pictures, &c., swing, 

 or to stop clocks : (d) To overthrow ornaments, vases, &c., or 

 cause plaster to fall from the ceiling : (^) To throw down chim- 

 neys, or make cracks in the walls of buildings ? 



(7) Sound-phenomena : («) If any unusual rumbling sound 

 was heard at the time of the shock, what did it resemble ? (3) 

 Did the beginning of the sound precede, coincide with, or follow, 

 the beginning of the shock, and by how many seconds ? {c) Did 

 the end of the sound precede, coincide with, or follow, the end 

 of the .-hock, and by how many seconds ? {d) Did the sound 

 become gradually louder and then die away ? {e) Were the 

 principal vibrations felt before, at, or after the instant when the 

 sound was loudest ? 



(8) The names of any other places where the earthquake was 

 noticed would be most useful, together with answers for each 

 place (if possible) to the following questions :—=(«) Was the 

 shock felt ? i^b) Was it strong enough to make doors, windows, 

 fire-irons, &c., rattle? (c) Was any unusual rumbling sound 

 heard at the time of the shock ? Charles Davison. 



38, Charlotte Road, Birmingham, August 23. 



CHEMISTR YA T THE BRITISH ASSOCIA TION. 



A FTER the President's address, the first paper was read by 

 Prof. Crum Brown on " Electrolytic Synthesis," descrip- 

 tive of work carried out in conjunction with Dr. J. Walker. 



He showed how, by an extension of the electrolytic methods 

 which had been already fully worked out in relation to potas- 

 sium acetate, the higher fatty acids of other series could be 

 synihesised. Thus, starting from the ethyl potassium malonate 

 the ether of succinic acid was obtained in considerable quantity 

 and with great readiness. Similarly adipic, sebacic and other 

 ethers had been obtained. Secondary products were formed 

 which in the higher members of the series accumulated in 

 inconveniently large quantities. 



Professor Ramsay gave a communication on the " Impurities 

 in Chloroform." He found that when the purest chloroform 

 that could be prepared was exposed to light between the months 

 of March and July, it emitted an acrid odour when opened, due 

 to the formation of phosgene gas. The reaction by which this 

 had been brought about was : — 



2CHCl3 + 02 = 2 COCI2-I-2 HCl. 



The second day of the meeting was devoted almost entirely 

 to the consideration of the phenomena accompanying the com- 

 bustion of gases. Messrs. Lean and Bone gave an account of 

 the results obtained in exploding ethylene with less than its own 

 volume of oxygen. They had found that there was always a 

 considerable rise of pressure, and that the' resulting products 

 contained, in addition to hydrogen and carbon monoxide, small 

 percentages of carbon dioxide, unsaturated hydrocarbons, and 

 some saturated hydrocarbon, presumably hiaish gas. 



The unsaturated hydrocarbons consisted largely, if not entirely, 

 of acetylene. Carbon is also formed as a product of the reaction, 

 due in all probability to the decomposition of heavy hydro- 

 carbons into marsh gas and carbon at high temperatures. The 

 experiments show that oxygen combines with carbon in preference 

 to hydrogen. 



Prof. Lewes, in his paper on the " Luminosity of Hydro- 



