July 24, 1913] 



NATURE 



539 



suggests that in periodic changes in the refraction 

 may be found in part the explanation of the dis- 

 crepancy between the values of the aberration con- 

 stanl derived from the solar parallax and that given 

 by Talcott's method. Further work can alone 

 elucidate the point. 



Engineering for July 18 gives an account of inves- 

 tigations made by the United States Bureau of Mines 

 on the ignition of mine-gas by glow-lamps. That all 

 types of glow-lamps are not equally liable to cause 

 ignition of explosive gas was known from previous 

 experiments, conducted chiefly in Belgium, France, 

 and Germany. The American investigators come to 

 the following chief conclusions: — The naked carbon 

 filaments of standard types of lamps, burning at rated 

 voltages, will invariably ignite explosive gaseous mix- 

 tures. If the gas can reach those filaments without 

 breaking them, or without producing partial com- 

 bustion within the bulbs, the gas is sure to be ignited. 

 Several, but not all, sizes of standard lamps (carbon 

 and metallic filaments) and of miniature lamps (small 

 lamp> lor miners) will ignite the gas when smashed 

 while burning at rated voltages; those lamps which 

 do not cause ignition usually, may do so if the broken 

 pieces of the filament produce a short circuit when 

 the lamps are smashed. Reviewing the results, all 

 the lamps tested must be considered unsafe, though 

 some specimens of a class might not cause ignition. 

 Alternating or direct current, and coupling in series 

 or parallel, made little difference. 



Messrs. J. and A. Churchill have nearly ready 

 for publication the seventh edition of "The Micro- 

 tomist's Vade-Mecum," by A. B. Lee ; the sixth 

 edition of the late Prof. J. Campbell Brown's "Prac- 

 tical Chemistry," edited by Dr. Bengough ; and the 

 third edition of "A Text-book of Physics," edited by 

 A. Wilmer Duff. 



The publication of a new series of books, entitled 

 "The Cambridge Technical Series," and edited by 

 Mr. P. Abbott, is being undertaken by the Cambridge 

 University Press. The series will be comprehensive 

 and will include the whole sphere of technical work 

 in the widest sense. Among the subjects arranged 

 for are : — Automobile engineering, electro-technical 

 measurements, chemistry and technology of oils and 

 fats, mining geology, and domestic science. 



A copy of their new list of wirefess apparatus and 

 accessories has been sent to us by Messrs. F. Darton 

 and Co., 142 St. John Street, Clerkenwell, London, 

 E.C. This firm has a long-distance installation at 

 work at its factory, and makes a practice of explain- 

 ing the most efficient methods of using the apparatus 

 supplied to customers. The list is well illustrated, 

 and full particulars of many forms of transmitting 

 and receiving apparatus are supplied. 



OUR ASTRONOMICAL COLUMN. 



Periodic Spectrum of a Canum Venaticorum. — 

 Prof. A. Belopolsky publishes in Astronomische Nach- 

 richten, No. 4664, the epochs of maximum intensity 

 of the dark line A = 4i2-993 fi/i in the spectrum of 

 a Canum Venaticorum. Fifty hours is stated to be 

 NO. 2282, VOL. 91] 



the length of time of the visibility of this line, and 

 the periodicity very near 550 days. Other lines 

 become faint at these epochs. 

 1913 July 24-96 G.M.T. Aug. 15-96 G.M.T. 



,, 30-46 ,, ,, 21-46 ,, 



Aug. 4-96 ,, ,, 269b 



,, 10-46 ,, Sept. r-4fa 



,, 6-96 

 Stars having Peculiar Spectra. — The observations 

 carried out by Miss Cannon for the Revised Draper 

 Catalogue have added already ten stars to those 

 known to have bright lines in their spectra, and 

 twenty-four new composite spectra. Details of these 

 are given in Harvard Circular 178. The bright-line 

 stars have spectra belonging to classes ranging be- 

 tween B3 and Oe. The latter shows the bands 

 AA4633 and 4688 bright, whilst H/3 is seen bright in 

 the rest, one also showing H7 as a bright line. Of 

 the twenty-four stars showing composite spectra only 

 four are included in Burnham's General Catalogue of 

 Double Stars. 



In the same circular it is remarked that a photo- 

 graph of the spectrum of Nova Geminorum No. 2 

 secured on April 5, 1913, shows only slight changes 

 since November 9, 1912, when the brightest band was 

 at A4363. Between AA4686-5007 the spectrum re- 

 sembles that of the prevailing type of gaseous nebulae, 

 but differences occur in other portions of the spectrum. 



The Origin of the Planets. — In a memoir com- 

 municated to the American Academy of Arts and 

 Sciences (vol. xiv., No. 1) Prof. P. Lowell arrives at 

 some interesting conclusions regarding the genesis of 

 the solar system. Inquiring into the causes of a 

 striking commensurability exhibited between the mean 

 motions of adjacent planets some of the deductions he 

 makes are : — (1) The planets grew out of scattered 

 material ; (2) each brought the next one into being 

 by the perturbation it induced; (3) Jupiter was the 

 starting point, and is the only one of the planets that 

 could have had a nucleus at the start. 



Prof. Lowell enunciates the following law : — " Each 

 planet has formed the next in the series at one of 

 the adjacent commensurable-period points, correspond- 

 ing to A, ';, J-, and in one instance § of its mean 

 motion, "each then displacing the other slightly sun- 

 ward, thus making of the solar system an articulated 

 whole, an inorganic organism, which not only evolved 

 but evolved in a definite order, the steps of which 

 celestial mechanics enables us to retrace." 



On the basis of this law he makes some predictions 

 retrardinff "the nearest trans-Neptunian planet "; thus 

 it should have a major axis of 47-5 astronomical units, 

 and a mass comparable with Neptune, though prob- 

 ably less. 



THE HULL MEETING OF THE MUSEUMS 

 ASSOCLA TION. 



THE annual conference of the Museums Association 

 was held at Hull last week, under the presidency 

 of Mr. E. Howarth. There was a large attendance, 

 including representatives from abroad, as well as from 

 numerous places in the British Isles. 



As his presidential address, Mr. Howarth gave a 

 helpful and suggestive discourse on the scope, func- 

 tion, and development of museums, using the word 

 in its most comprehensive sense. He pointed out that 

 though the universe could not be represented in a 

 museum, yet even the provincial institution was doing 

 work of a national character. It would be foolish 

 to attempt to reproduce the British Museum in every 

 town, but the principles dominating it were applicable 

 to the smallest village museum. Museums should 



