488 



SCIENCE. 



[Vol. II., No. 36. 



his pea have appeared in the Botanischp, 

 zeitung, Bienen zeititng, Kosmos, Nature, 

 etc.. while, as editor of the department of 

 Justs' JaJiresbericht, relating to pollination 

 and dissemination, he has contributed reviews 

 of all of the more important publications bear- 

 ing on his specialty. Beside these, he pub- 

 lished two books, — Befruchtung der blumen 

 durch insekten, und die gegenseitigeu anpas- 

 sungen beider (which appeared in 1873, served 

 as the basis of a verj- instructive series of arti- 

 cles in Nature, and was largely' drawn upon 

 by Lubbock in the preparation of his little 

 work on British wild-flowers, and which, sup- 

 plemented hy the more recent observations of 

 its author, has latelj' been translated into 

 English) ; and Alpenblumen, ihre befruchtung 

 durch insekten und ihre anpassuugen an die- 

 selben (a volume of equal size, published in 

 1881, and, like its predecessor, filled with 

 instructive facts)'. 



From the first. Dr. Miiller was a pronounced 

 evolutionist, perhaps erring in too exclusive 

 contemplation of a limited part .of the evi- 

 dence of derivation^ and, like manj' others of 

 the German school, incline'd to push evolution- 

 arj' logic to its ultimate if undemonstrable 

 conclusion of materialism. 



As a teacher he was most excellent, having 

 the facultj', not only of imparting ideas to his 

 pupils, but of inspiring their enthusiasm. In 

 his specialty he was a careful observer, noting 

 and accounting for many minute structural 

 peculiarities in both flowers and insects, which, 

 so long as their utility* remained undiscovered, 

 were explicable onl^- bj- the theory of types in 

 nature. So far as observation is concerned, 

 his work is above criticism. As a rule, too, 

 his inferences are correctlj- drawn, though the 

 limitation of his studies to a small part of the 

 world has at times rendered his enthusiasm 

 over the biological significance of some sup- 

 posed new adaptation, subject to the criticism 

 of specialists previously familiar with the struc- 

 ture, if not with its meaning. 



As a friend, Dr. MiiUer was alwa3's cordial, 

 ever ready with encouragement and assistance 

 for j'ounger workers in the line of his specialty. 



He had, however, little patience with inac- 

 curacj' in observation, and, both publicly and 

 in private, criticised errors with vigor ; but, 

 though his criticisms were sometimes severe, 

 they were seldom unkind, and never unjust. 

 By his death, biological science loses not only 

 one of its most enthusiastic and able devotees, 

 but also one, who, by the independent and 

 thorough nature of his work, may be styled 

 not inappropriately an epoch-maker. 



THE USE OF THE SPECTROSCOPE IN 

 METEOROLOGY. 



In April last it was thought desirable to add 

 to the regular meteorological observation made 

 at the Shattuck observatory, Dartmouth col- 

 lege, the hygro metric indications of the spec- 

 troscope. The observations were made in 

 accordance with the directions of J. Rand 

 Capron in his ' Plea for the rain-band.' The 

 instruments used were two direct vision spec- 

 troscopes : one a 3^-inch ' vest-pocket ' in- 

 strument of Hofmann's ; the other 10 inches 

 in length, and capable of separating the D lines 

 with direct sunlight. The observations made 

 in this waj' were found to be interesting, but 

 unsatisfactory. The difficulty which an ob- 

 server must alwaj's find in estimating confi- 

 dentl}' the degree of intensity of tlie absorption 

 lines and bands with the widely varying lights 

 of fair and cloudy weather, makes the arrange- 

 ment of some method of measurement verj- 

 desirable. After a few trials in other direc- 

 tions, the device described below was decided 

 upon, and has proved satisfactory. It was 

 tliought that the absorption lines of aqueous 

 vapor, seen with a spectroscope of rather high 

 power, are better adapted to delicate measure- 

 ment than the broad band seen with a low 

 power. The small spectroscope used shows 

 the dark band on the red side of the D line 

 with great clearness ; but the absorption lines 

 are onlj- visible when particularly- strong. 

 With the larger instrument, however, the spec- 

 trum is so elongated that the general darken- 

 ing near D is hardly noticeable ; while the two 

 moisture lines to be found there are ver^- 

 prominent. The apparatus illustrated is de- 

 signed to measure the variation in intensitj- of 

 the darker line of this pair (the a of the D 

 group of Janssen's map). 



The only methods of measurement of the 

 intensitj- of absorption lines, known to the 

 writer, are those of Janssen and Gouy. The 



