170 REPORT— 1877. 



which it always possesses more or less strongly, as described above in Mr. 

 Clark's and Mr. Denning's observations. While the words " train " or " tail," 

 used to denote " something bright " in a meteor's wake distinct from the head, 

 are perfectly ambiguous (since they would equally be used to denote sparks 

 and flakes or detached embers of every kind which meteors leave or draw 

 after them along their course), the word " streak," implying the mark im- 

 pressed or impiiuted by the meteor upon the air when its velocity and heat 

 are great enough to make this visible, is incapable by its ordinary signification 

 of being applied to fragments of the meteor itself, such as constitute the great 

 variety of glowing products or residues which are often observable during 

 the process of a good many meteors' deflagrations ; but in its proper meaning 

 of a mark made or left by a meteor upon the atmosphere, it probably ex- 

 presses the real origin of the above-described vapours or cloud-like evolutions 

 of light sometimes produced along a meteor's track. Such streaks (as they 

 should be called) are not always white, nor oven, when very permanent, of 

 unchanging colours ; for those of the Perseids are sometimes orange-yellow, 

 and those of the Leonids bright green, changing when long-enduring to white 

 and yellow, and even occasionally to dull red beforo they fade away ; and in 

 their spectra the lines of incandescent magnesium-vapour have been found to 

 be visible up to the extinction of a streak for noarly a quarter of an hour, 

 showing that they are composed of some self-luminous gases in whose light 

 it is believed that the lines of several metallic vapours have been observod. 

 The words " streak " and " no streak," denoting whether a meteor left or 

 did not produce a hue of phosphorescence or of kindling and ignited gases 

 along its line of flight, should not be omitted in recording the appearance 

 of even very faint and inconspicuous shooting-stars ; while the words " traiu " 

 and "tail," or " track of sparks," &c, should never be employed to denote 

 it even it' its brightness is very marked, but should be used exclusively to 

 describe those luminous appearances in a meteor's flight which evidently 

 proceed from more or less pulverized solid portions of the meteor's substance 

 separated from it in its flight, and which, however luminous at first, in general 

 soon become extinguished. 



A very complete review of his observations in November and December, 

 1876, was given by Mr. Denning in the ' Astronomical Register ' of Dec. 

 1876 (p. 296) and January 1877 (p. 18), to the very carefully compiled 

 results of which sufficient reference will here be made by this allusion. 

 Besides about 30 meteors mapped from September 10th to 20th (which 

 gave nearly the same radiant-points as the October tracks), 122 meteors were 

 mapped from October 13th to 29th, and 183 meteors from November 8th to 

 30th ; the former group presented 16, and the latter 18 meteor-showers. As 

 a class they were small, and mostly white and swift, the magnitudes of 306 

 which were registered between October 13th and November 28th being thus 

 distributed, beginning with those equal to or exceeding stars of the first 

 magnitude in brightness, and reckoning in their order those equal to the re- 

 maining inferior magnitudes of the fixed stars to the 6th inclusive : — 



1st mag. or brighter, 19 ; 49 ; 61 ; 107 ; 65 ; 5 sixth mag. Total 306*. 

 During the first half of December 117 meteors were registered, principally 



* On the Gth of December, 1876, Mr. Denning counted 14 stars of tlie Pleiades distinctly 

 with the naked eye ; and be varied the monotony of a long and fruitless watch for the 

 Lyrids on the night of April 19th-20tb, 1877, by glimpses of Winnecke's telescopic comet, 

 in Lacerta, without instrumental aid. This acuteness of vision will perhaps account for 

 many small meteors being noted in his records which would have passed unnoticed, and 

 even have escaped detection by the eyes of observers less sensitive to exceedingly faint objects. 





