January 1, 1886.] 



SCIENCE. 



9 



worthy. The average transmission of the lunar rays 

 by glass during the eclipse was about twenty-two per 

 cent, and did not differ very materially from that 

 for the uneclipsed moon on this day. If the increased 

 transmissibility at the outer edge of the umbra be a 

 real effect, it is possibly local and evanescent. 



The deflection obtained from a portion of the 

 lunar surface just in advance of the umbra did not 

 very materially differ from that given by a similar 

 portion over which the umbra had just passed. 



Clouds, preventing further observations, began to 

 form as the penumbra was about passing off. There 

 were indications, however, of a recovery of heat 

 nearly as rapid as the previous fall. This effect was 

 shown, though in a less marked manner, by Dr. 

 Boeddicker's observations, in the eclipse of Oct. 4, 

 1884, made at Lord Rosse's observatory (see Nature, 

 xxx. p. 589). 



The following are the deflections observed on each 

 point during the progress of the eclipse at Allegheny : 





tion. 



Time. 



Time 

 from 

 mid- 

 eclipse. 





Deflec- 

 tion. 



Time. 



Time 

 from 

 mid- 

 eulipse. 





Deflec- 

 tion. 



Time. 



Time 

 from 

 mid- 

 eclipse 







h. m. 



h. m. 



Pen 





h. m. 



h. m. 







h. m. 



h. m. 



East 



164 



11.53 



2.35 



tre. 



18 



12.01 



2.27 



West 



155 



12.16 



2 12 





125 



12.26 



2.28 





12* 



12.44 



1.44 





15.5 



12.32 



1.56 





45 



12.53 



1.35 





101 



1.06 



1.22 





12S 



12.53 



1.30 



N.E. 



4 



1.28 



1.00 





31 



3.49 



1.21 





21 



4.05 



1.37 



S. E. 



71 



3.43 



1.15 



















The salient feature of these observations is, we 

 need hardly say, the extraordinary rapidity with 

 which the lunar surface parts with its heat, most of 

 that which is radiated disappearing all but simul- 

 taneously with that reflected. S. P. Langley, 



Allegheny observatory, Dec. 23. 



Sir William Thomson to the coefficients. 



I know of no easier way to reach those for whom 

 the enclosed message was especially intended than 

 through the columns of Science. At the same time, 

 I believe it will be read with great interest by many 

 who were not of the somewhat limited number re- 

 ferred to. To such, a brief explanation may be 

 due : — 



At the close of the course of lectures by Sir William 

 Thomson, at Baltimore, in October, 1884, it was 

 determined by those who, through the courtesy of 

 the Johns Hopkins university, had enjoyed the privi- 

 lege of listening to the course, to present Sir William 

 with a memento of the occasion which had been, to 

 them, of such unusual interest. Under the circum- 

 stances, nothing could have been more fitting for this 

 purpose than one of Professor Rowland's large con- 

 cave gratings, which was accordingly agreed upon. 

 Several months were required for the manufacture 

 and examination of a grating which was entirely 

 satisfactory to Professor Rowland ; but early in the 

 past summer it was completed, and transmitted to 

 Sir William Thomson through the kindness of the 

 secretary of the Smithsonian institution. 



Prof. George Forbes of London was present during 

 the course of lectures, and Lord Rayleigh attended a 

 number of them. In the equations of motion devel- 

 oped in the work there appeared twenty-one coeffi- 

 cients, agreeing in number nearly, if not exactly, 

 with the number of persons in regular attendance 



upon the lectures. This relation was quickly noticed 

 by some one, and was made the basis of some humor- 

 ous verses composed by the genial and witty Forbes, 

 which were read at a reception given to the class by 

 President Gilman, and were afterward published. 

 Their title was "The lament of the twenty-one co- 

 efficients in parting from each other and from their 

 much-esteemed molecule." 

 The first stanza began, — 



" An aeolotropic molecule was looking at the view. 

 Surrounded by his coefficients, twenty one or two; " 



and the whole will always possess much interest to 

 those who were present. With this explanation, I 

 justify the title which I have given to the following 

 selections from a letter recently received from Sir 

 William Thomson. T. C. M. 



Washington. D.C., Dec. 28. 



I wrote to Professor Rowland, acknowledging the 

 receipt of the grating ; but I ought before now to 

 have thanked all the other coefficients for their kind- 

 ness in giving it to me. I should feel greatly obliged 

 if you would transmit to those of the coefficients who 

 are in America my heartiest thanks for their great 

 kindness, and say to them that the grating will be a 

 permanent memorial to me of the happy three weeks 

 of 1884, when we were together in Baltimore. . . . 

 After the British association meeting at Aberdeen, 

 I was delighted to be able to show the grating to 

 some of our English appreciators, — including one of 

 the coefficients, George Forbes ; and Lord Rayleigh, 

 whom we may consider as, at all events, a partial 

 coefficient ; and Professor Fitzgerald of Trinity col- 

 lege, Dublin ; Oliver Lodge of Liverpool ; Glaze- 

 brooke of Cambridge ; and Captain Creak of the 

 compass department of our admiralty, — who came 

 to stay with us at Netherhall, our country house, 

 for a few days, on their way south. We had no 

 sunlight to work with, but we got the double sodium 

 light in the first and second spectrums from a salted 

 spirit-lamp flame exceedingly well, and we were all 

 delighted with the result. I had never myself seen 

 any thing like it before. William Thomson. 



The university, Glasgow, Dec. 5. 



A waste of public money. 



My attention has just been drawn to your notice in 

 Science of Dec. 4, of my forthcoming report on irri- 

 gation. The substance of your criticism is that quan- 

 tity, and not quality, appears to have been the object 

 in its compilation, — that the work should have been 

 written in one volume instead of three ; and you 

 quote a long, redundant paragraph as a sample of the 

 composition throughout. 



It is to be regretted that you undertook to criticise 

 an entire report, when you had before you only some 

 advance sheets of one volume, very hastily printed 

 from unrevised manuscript, solely for the purpose of 

 an exhibit to the legislature, which desired to know 

 something of the scope of the work. 



The entire report, as ordered printed, is now under 

 way ; and I believe you will find, when you receive 

 a copy, a decided improvement in the literary con- 

 struction which you have criticised. As for the 

 general make-up of the work, — its fulness, and oc- 

 casional repetition of matter under different head- 

 ings, — which you do not specially refer to, but proba- 

 bly have noticed, I shall have something to say at the 



