February 5, 1886 ] 



SCIENCE. 



123 



bodies of ordinary temperatures, and a% for that 

 from the sun ; and this distinction is made through- 

 out, in all the numerous equations into which the 

 radiated heat of the sun enters. 



The necessity for this, which at the time was con- 

 sidered only highly probable, is now fully shown by 

 Mr. Langley's recent very interesting- and important 

 experiments on invisible heat spectra (Amer. journ. 

 sc., January, 1886). It requires a glance only at the 

 graphic representation of his results (place iii.) to see 

 that when the temperatures of the bodies differ, the 

 absorbing power of the body of lower temperature, 

 for the heat of a body cf higher temperature, is 

 greater than the radiating power at the end of the 

 spectrum of short wave-lengths, and the reverse at 

 the other end. Hence, where there is selective ab- 

 sorption, as there usually is more or less where any 

 part of the heat is reflected, the radiating and ab- 

 sorbing powers of a body, for the heat-rays as a 

 whole, may not be equal. If the reflected heat were 

 considerable, and mostly of the rays of either end of 

 the spectrum, the difference might be considerable. 

 The amount of beat reflected by the moon is probably 

 much less than that radiated, and the white light of 

 the moon does not indicate that there is much, if 

 any, selective reflection. There cannot, therefore, be 

 much difference between the radiating and absorbing 

 power of the moon for the sun's heat-rays taken col- 

 lectively. The little difference which there may be 

 would, of course, affect my result slightly. If the 

 absorbing power were a little greater than the ladi- 

 ating power, then the temperature of the moon 

 would have to be a little higher to radiate as much 

 heat as it receives and absorbs. It is seen from 

 what precedes that the possible inequality of radiat- 

 ing and absorbing powers has not been overlooked, 

 and was provided for in my paper referred to above, 

 at a time when there was scarcelj' a suspicion with 

 regard to the general applicability of the law. But 

 its greatest possible effect on my result was con- 

 sidered of too little consequence to refer to in a 

 short communication on a matter in which, at best, 

 we can expect only approximate results. It is true 

 that the equality of the radiating and absorbing 

 powers was one of my conditions, and that the result 

 is strictly true only for this assumed equality, and 

 that this is therefore one of the 'limitations.' But 

 it does not seem that the ' airless body ' should be put 

 into the ' endless list ; ' for I think that astronomers 

 are very nearly, if not quite, unanimous in the opin- 

 ion that the moon has no atmosphere which can 

 sensibly affect its radiations. 



My conditions, strictly, are for mean or stationary 

 temperatures only ; but they are applicable without 

 sensible error to the case of the varying distance of 

 the moon, on account of the slowness with which the 

 distance and the corresponding temperature change. 

 With regard to the lunar diurnal variations, the con- 

 ditions determine nothing more than the limit beyond 

 which the maximum temperature of any part of the 

 moon's disk cannot go ; but this is all that has been 

 claimed. If the method is not of general application, 

 or the results deduced extremely accurate, I think 

 they are not to be despised where we, as yet, know 

 scarcely any thing. The laws of Kepler were im- 

 portant in his time, notwithstanding they did not 

 take into account the ' endless list' of perturbations. 



I am sorry Mr. Langley has resolved to have 

 nothing more to say on these interesting subjects, 

 for there are many things, somewhat in common 



with our separate lines of research, which I would 

 like to discuss in a candid and friendly manner. 



Wm. Ferrel. 



Washington, Jan. 28. 



Professor Newcomb's address before the Ameri- 

 can society for psychical research. 



In your editorial note of Jan. 29, on Professor 

 Newcomb's presidential address to the American 

 society for psychical research, reference is made to 

 his ' very acute observation ' that in certain draw- 

 ings published by the English society as apparent 

 results of thou^ht-transferrence, " the lines join per- 

 fectly, as would be the case with the work of a 

 draughtsman who could see, and this too in the 

 drawings made blindfold." You go on to say that 

 ' the natural inference is that there was some 

 trickery ; ' and you add, that the English society's 

 work ' bears the character of that of amateurs and 

 enthusiasts.' I think you ought, in justice, to let 

 your readers know that the drawings particularly 

 referred to in the address were five in number. Of 

 the series to which three of these belong, it is con- 

 spicuously said, in the accompanying report, that, 

 4 as regards the bandage round his eyes,' the 

 draughtsman ' sometimes pulls it down before he 

 begins to draw.' The two other drawings belong to 

 a series which the report says were executed while 

 the draughtsman ' remained blindfolded.' But, if 

 Professor Newcomb will himself try to reproduce 

 these drawings with his eyes closed, he may perhaps 

 be led to agree that their accuracy can hardly be 

 deemed to fall outside the range attainable by the 

 muscular sense alone, especially if aided by a little 

 practice. To brand as dupes and enthusiasts (on the 

 strength of this single ' acute observation ') a set of 

 gentlemen as careful as these English investigators 

 have proved to be, seems to me singularly unjust. 



William James. 



Cambridge, Mass., Jan. 30. 



Death of Father Gaetano Chierici. 



Prehistoric archeology in Italy has just met with a 

 most serious loss in the sudden death, on the 8th of 

 last month, of Father Gaetano Chierici, professor in 

 the college at Eeggio, in Emilia, and director of the 

 admirable Museum of antiquities, in that city. In 

 association with Professor Strobel of Parma, and 

 Professor Pigorini, director of the Ethnographic mu- 

 seum, at Eome, he founded, and has continued to 

 edit, the Bulletino di paletnologia Italiana, a monthly 

 journal of prehistoric science, now entering upon its 

 twelfth year. Indefatigable in his prehistoric explo- 

 rations, he is best known for his investigations of 

 the remarkable Ter re mares of Emilia, which have 

 established the existence of the age of bronze in that 

 country. His last work was to superintend the exca- 

 vation and transport to Reggio of several tombs from 

 a very ancient cemetery discovered at Renedello, 

 near Brescia. This seems to belong to a period of 

 transition from the age of polished stone to a time 

 when weapons of copper were used, anterior to the 

 age of bronze. Chierici believed that they are re- 

 mains of the aucient, obscure Pelasgic race. 



It is proposed to place a simple bust to the memory 

 of this modest and learned ecclesiastic in the museum 

 which he so admirably arranged and illustrated, and 

 of which he deserves to be called the founder. Con- 



