Maecii 2, 1883.] 



SCIENCi:. 



95 



ing above the mountain summit on the morning 

 of the 2d, but it had vanished completely 

 within two hours ; and on three or four occa- 

 sions clouds were observed ver^' near the hori- 

 zon, but they never rose. Fitful gusts of 

 wind prevailed night and day the 3d and 4th, 

 and the morning of the 5th ; but, about uoon 

 this latter daj-, a period of the utmost tran- 

 quillitj' set in, and lasted for fifty or sixty hours, 

 the temperature ranging only between sixty 

 and seventj' degrees. 



Dec. 6 the sun rose about seven o'clock, 

 with Venus a good way ou its disk. The first 

 sensitive plate was exposed at eleven minutes 

 after seven, the slit being three inches wide, 

 and the exposure a second and a half long ; 

 but a verj' faint image was all that came out 

 on the plate in developing. Six minutes later, 



sixths of them will be available for exact 

 micrometric measurement. Their number and 

 quality' are about as follow : A signifj'ing a 

 plate of the first order of definition, and anj' 

 two successive grades being separated by onl}' 

 a slight variation iu quality : — 



Grade. 

 A 



A- 

 B-l- 

 B 



No. of 

 Photographs. 



71 

 23 

 13 

 9 



Grade. 



B- 



C 



No. of 

 Photographs. 



Total, 



The record of the times of exposure of these 

 photographs was kept by two chronometers 

 independently, one record being automatic. 

 The original photographic record, and such 

 parts of the photoheliograph as have j^et to be 

 investigated, together with the greater part of 



TITANOPHASMA FATOLI ERONGNIAT. — ONE-FOURTH NATU 



with an exposure of one second, a picture 

 sufflcientlj' intense for measurement was ob- 

 tained ; but the vertical diameter of the sun 

 was about a quarter of an inch, or one-eigh- 

 teenth part, shorter than the horizontal one. 

 Something like a half-hour later, verj' satisfac- 

 tory pictures began to be obtained, with the 

 slit an inch wide, and an exposure less than 

 half a second long. Bj' twentj- minutes past 

 nine the slit had been reduced in width to 

 0.25 in., and was kept at this setting through- 

 out the remainder of the transit, the exposures 

 varying onlj' slightly from 0.25 sec. in length. 

 At twenty-two minutes before twelve the last 

 exposure preceding interior contact at egress 

 was made, and subsequently ten additional 

 photographs were taken between the two con- 

 tacts. The total number of plates exposed 

 was a hundred and forty-seven, and about five- 



the photographs themselves, are now stored 

 for safe-keeping in the vault of the observatory 

 on the mountain. 



No other observations of importance were 

 attempted, except those of the two contacts at 

 egress : these being observed bj' Capt. Floj'd, 

 with thetwelve-inch equatorial, aperture reduced 

 to six inches ; and by myself, with the four-inch 

 transit instrument. David P. Todd. 



A GIGANTIC WALKING-STICK FROM 

 THE COAL. 



We owe to the favor of M. Charles Bron- 

 gniart of Paris, sketches of an enormous insect 

 from the carboniferous beds of Commentrj^ 

 France, which we have reproduced upon this 

 page ; m short preliminary notices, given last 

 December to the Paris academy and the geo- 



