242 



THE POPULAR SCIENCE MONTHLY. 



or absence of rain for very want of material to make it ; and the band 

 has, therefore, been called, shortly, " the rain-band." Thus, also, "rain- 

 band spectroscopes " have been specially constructed by several most 

 expert opticians in size so small as to be carriable in the waistcoat- 

 pocket, but so powerful and true that a glance of two seconds' dura- 

 tion through one of them suffices to tell an experienced observer the 

 general condition of the whole atmosphere. Especially, too, of the 

 upper parts of it, where any changes as they take place there almost 

 invariably earlier than below enable such an observer to favor his 

 friends around him with a prevision of what they are likely soon to 

 experience. 



As an example of what may be done, and done easily, after a cer- 

 tain amount of experience and understanding of the subject has been 

 acquired, I append, from a lady's meteorological journal, her notes of 

 the mean temperature of the air and the intensity of the rain-band for 

 each of the first fifteen days of the present month, and in a final col- 

 umn have entered the amount of rain-fall measured at the Royal 

 Observatory, Edinburgh, on each of those davs. The darker the rain- 

 band the larger is the figure set down for it, and it will be seen pretty 

 plainly, on running the eye down that column and the next one, that 

 with an intensity of either or 1 no rain follows, or, we might almost 

 say, can follow ; but with an intensity of 2 rain-fall begins, and with 

 3 it may be very heavy. All these rain-band notes have been made 

 with a spectroscope no larger than one's little finger, purchased some 

 six years ago, and taken on many voyages and travels since then : 



DATE, September, 18S2. 



Friday, 1 



Saturday, 2 . . . 



Sunday, 3 



Monday, 4 . . . . 

 Tuesday, 5 . . . . 

 Wednesday, 6 . 

 Thursday, 7 . . . 



Friday, 8 



Saturday, 9 . . . 

 Sunday, 10 

 Monday, 11... 

 Tuesday, 12. . . 

 Wednesday, 13 

 Thursday, 14 . . 

 Friday, 15. 



Mean tem- 

 perature of the 



Deg. Fahr. 

 571 

 59-2 

 5S-6 

 54-4 

 55-7 

 55-2 

 53-8 

 59-4 

 54-0 

 57-0 

 52-2 

 48-6 

 528 

 49-5 

 56-2 



Bain-band 

 intensity. 



Depth cf rain 



measured in 



gauge at Koyal 



Observatory, 



Edinburgh. 



3 



2 

 2 

 

 1 

 

 1 

 



1 

 1 

 1 







1 



3 



2 



Inch. 

 044 

 353 

 015 





























 040 











62 

 .570 



But, if so much can be done by so small a spectroscope, the ques- 

 tion may be well asked whether more still might not be accomplished 

 with a bigger and more powerful one, especially seeing that the dis- 

 persive powers of both chemical and astronomical spectroscopes have 



