1^.2 



NATURE 



[June i i, 1903 



a few doublets. Nos. 722 and 723 are charming patterns 

 in snow architecture, 



November 30.— Clouds rather thin stratus and nimbus. 

 Crystal types wholly tabular of both open and stellate 

 structure (Fig. 2, Nos. 730-737). 



Among the seven forms of this date we find much to 

 admire in the perfect beautv and symmetry of Nos. 731-734- 

 The beautiful starfish design exhibited by No. 735 is some- 

 what rare. It is noteworthy that Prof. S. Squinabol, of 

 the University of Padua, made drawings of a snow crystal 

 found in Genoa in 1887 that closely resembles this latter 

 one. The star with long slender rays deposited during this 

 same storm, on November 26 (see' No. 712), also closely 

 resembles one figured by Squinabol in his work " La 

 Navigata. " No, 737 is another form that closely resembles 

 some of those secured by other observers ; it is very similar 

 to some of the photomicrographs secured by Dr. Neuhaus, 

 of Berlin, during the winter of 1893, and published in Dr. 

 G. Hellmann's work. 



December 4. — Clouds stratus, with detached running 

 masses of low nimbus ; probably high cirro-stratus above 

 these. The western portion of this cold southern storm 



Fig. 6.— Nos. 876-: 



furnished a great number of forms of snow crystals that 

 were in general rather small and compact. 



The rare beauty of Nos. 745, 748 (Fig. 3) will appeal to 

 all ; crj'stallographers will find much of interest in No. 749. 



1902, January 5. — The clouds of the western edge of the 

 storm of January 5, 1902, furnished a large and splendid 

 set of forms. Nos. 783, 785, 786, and 788 (Fig. 4) are 

 exquisite examples of the frail, branching type of crystals. 

 Xo. 785 is so rarely beautiful that Mr. Bentley describes 

 it as the peer of any in his whole collection. 



January 12. — Clouds obscured by heavy snowfall. A long 

 series of magnificent snow crystals was secured from the 

 clouds of the south-west-central portion of the storm or 

 blizzard of January 12 (see Nos. 816-824, Fig. 5). The 

 snow, as usual whenever it comes from the central-western 

 portion of a storm, consisted of a great variety of types 

 both columnar and tabular, but as the storm's central portion 

 passed farther to the east, during the afternoon of January 

 12, the columnar forms ceased to be deposited. Nos. 818, 

 821 and 822 possess much beauty of design and perfection 

 of form. 



February 8. ^Clouds stratus and nimbus ; probably high 

 cirro-stratus superimposed above them. A continuation of 

 the storm of F"ebruary 7, and its increase in rigour furnished 



NO. 1754, VOL. 68] 



more forms than were ever before secured bv Mr. Bentb 

 from any one storm. The beautiful branching" crystals, N( 

 881 and 883 (Fig. 6), portray, in general, the characters . 

 the forms tha't successively replaced both the solid tabul; 

 and columnar forms, as the western edge of the storm can 

 nearer. No. 884 exhibits a most interesting phase 

 crystallic evolution ; it is composed of four contiguous poini 

 or rather portions, and two somewhat stunted portions, al 

 similar to each other, but differing widely from the oth 

 four. No. 885 shows two overlapping additions to two 

 the points, thus rendering it of more than usual interr 

 and presenting us with another seemingly unsolvali 

 problem in crystallography. 



In concluding this mention of individual forms, it i^ 

 worthy of note that, as during previous winters, occasionally 

 single individual crystals, and more rarely larger numbers 

 of such, produced during the storms of this winter, re- 

 sembled closely, in outline or interior details, or oddity, one 

 or more of the individual forms found among the snows 

 of previous winters. The recurrence of similar types, after 

 perhaps long intervals of time have elapsed, is a phenomenon 

 of great interest. ' 



In conclusion, it may be worth noting that by the addition 

 of more than 200 plates during the past winter, the number 

 of individual photomicrographs of crystals in Mr. Bentley's- 

 collection is brought up to somewhat more than 1000, no 

 two of which are alike. This completes also his seventeenth 

 year of photographic work among the snow crystals. 



DR. A. A. COMMON, F.R.S. 



IT was with deep regret that the news of the sudden 

 death of Dr. Common had to be announced in the 

 last number of this Journal. Dr. Common was so hale 

 a:nd hearty that it came as a great shock to his friends 

 to find that he was no more, and his loss is felt not 

 only by a great circle of friends, but by the astronomical 

 world at large. Born in 1841, August 7, Dr. Andrew 

 Ainslie Common was by profession an engineer, but 

 quite at an early date he turned his attention to 

 astronomy. In 1874 he became the possessor of a 

 5^-inch refractor, and three years later of an 18-inch 

 reflector by Calver. It was evidently the use of the 

 latter instrument which sowed the seed for his later 

 important researches in the making and silvering of 

 both large and small mirrors. An idea of his remark- 

 able energy and success in the grinding and silvering 

 of mirrors can be gathered from the following list of 

 large reflectors in use which he referred to in his 

 presidential address to Section A (Department of 

 Astronomy) of the British Association in 1900. This 

 list only referred to reflectors of 2ft. 6in. and upwards, 

 and out of the nine given five were from his own 

 workshop. 



Reflectors of 2 ft. 6 in. and upwards. 



Lord Rosse 



Dr. Common 



Melbourne 



Paris 



Meudon 



Solar Physics Observatory (Com non) 



Crossley (Lick; Common) 2 ° 



Greenwich (Common) ... ... ... ... 2 6 



Solar Physics Observatory (Common) ... 2 6 



His knowledge of engineering was a valuable ad- 

 junct in the designing and construction of the mount- 

 ings for his large mirrors. Dr. Common paid great 

 attention to this latter question, for on it depended to 

 a very great extent their efficiency and utilisation. He 

 eliminated the " tube " by substituting a light frame- 

 work of iron w^hich reduced air currents to a mini- 

 mum ; adopted a new method to prevent the mirror 

 being strained ; mounted large mirrors equatorially by 

 the ingenious device of reducing the friction of the 

 moving parts by floating them in mercury; designed 



