A good method of tabulating meteor-tracks is that adopted by Lieut.-Col. Tupman in his catalogue published by the British Association in 1874. I have adopted the same form, and herewith append a copy of my register of a few isolated bright meteors observed in the autumn of 1890:—
+————————+——————+——————+————————————————————-+——————+————-+ | | | | Observed Path | | | | Date |G.M.T.| Mag. +————————-+——————————-+Length|Dura-| | 1890. | | | From | To | of |tion.| | | | |R.A. Dec.| R.A. Dec | Path.| | +————————+——————+——————+————————————————————-+——————+————-+ | | h m| | o o | o o | o | sec.| |Oct+. 17| 10 37| >1 | 219+61 | 255+65 | 16 | 3·5 | | 19| 10 35| 1 | 61½+26 | 44½+27½ | 15½ | 0·7 | | 19| 12 0| ½ ☽ | 326-8 | 319-10 | 7 | 0·5 | | 25| 17 18| >♃ | 168+34 | 180+24 | 14½ | 0·8 | | 26| 7 33| ♃ | 329+69 | 243+51 | 42 | 4·0 | |Nov. 1 | 7 1| >1 | 278+49 | 244+11½ | 46 | 6·0 | | 1 | 9 17| >1 | 345+11 | 307+1½ | 39 | 4·0 | | 5 | 10 40| >♀ | 28½-25 | 25½-29½ | 5½ | 0·7 | | 16 | 11 15| ♃ | 274+77 | 265½+67 | 10 | 1·5 | +————————+——————+——————+————————————————————-+——————+————-+ +————————+—————————————————————+————————+ | | | | | Date | Appearance. |Probable| | 1890. | |Radiant.| | | | | +————————+—————————————————————+————————+ | | | o o | |Oct+. 17| V. slow, B. train. | 204+56.| | 19| Swift, streak. | Orion. | | 19| Swift, streak. | Orion. | | 25 |Swift, streak. | Lynx. | | 26| Slow. | 32+18. | |Nov. 1 | Very slow. | 50+15. | | 1 | Slow. | 50+15. | | 5 | Swift, strk. 15 sec.| Taurus.| | 16 | Not very swift. | Auriga.| +————————+—————————————————————+————————+
The _duration of flight_ is a most important element to estimate correctly, as it affords data wherewith the real velocity may be computed, and enables the nature of the orbit in which the meteor is moving to be definitely assigned. This feature is, however, one of the most difficult of all to derive with satisfactory precision. In the case of very slow meteors lasting several seconds, it is easy by means of a stop-watch, or by other methods, to get the times of flight within narrow limits of error, but the swifter class of meteors complete their visible trajectories in the fraction of a second, and are gone before any effort can be made to gauge their durations, so that a value has to be attributed which is little better than a mere guess.