OBSERVATIONS OF LUMINOUS METEORS. Gl 



courses with the brightest ncighbouriug fixed stars, to overstate rather than 

 to underrate the apparent length of their visible flights, will perhaps account 

 for the excessive real velocity of the Perseids obtained in these results of the 

 simultaneous observations. The velocity of a single meteor of the shower, 

 as bright as Sirius (the first meteor shown in the diagram), unconformable 

 to Perseus, and directed from the radiant-point in Pegasus, was somewhat 

 more exactly obtained, both its apparent path and its duration being very 

 carefully observed by 'Mr. Wood at Eirmingham and Mr. Clark at York, 

 whose observations were in excellent agreement. The real length of the path 

 of this meteor was 38 miles, and its resulting real velocity was 19 miles 

 per second. 



On comparing together the observations of the shooting- stars recorded at 

 Greenwich with those seen at the British-Associatiou stations during the 

 same August shower, several perfcctlj- accordant observations were found on 

 the night of the 11th; and but few satisfactory identifications of meteors 

 doubly observed on the night of the 10th of August, excepting that of the 

 brightest (at 10'' 51" p.m., as noticed in the following descriptions of the 

 shower), could be detected. The following list contains a general description 

 of the various shooting-stars which appear to have been doubly observed at 

 the Eojal Observatory, Greenwich (and by the observers at other stations), on 

 the night of the 11th of August, and on the other nights of simultaneous watch 

 kept for the reappearance of the annual meteor-showers which have been 

 visible during the past year. 



A few double observations of shooting-stars are also contained in the accom- 

 panying list of bright meteors, and in the detailed accounts which will shortly 

 be given of the observations of the meteoric showers. The meteor No. 7, 

 whose real height is figured in the above diagram from observations at York, 

 at Hawkhurst, and in London, was also seen at the Eoyal Observatorj', 

 Greenwich, and its apparent path was there recorded at ll*" 14™ 59" r.Ji. 

 on the 11th of August. The redetermination of the real height of this 

 meteor by comparison of the new observation with the former ones, and the 

 computation of the several meteor-heights to be derived from the additional 

 observations contained, in this Eeport, will afibrd interesting materials for 

 future consideration. 



The last meteor in the accompanying list, on the 19th of April last, wiU be 

 seen to have been triply observed at York, Wisbeach, and Hawkhurst. The 

 heights determined from the observations at the first two places are 66 miles 

 at first appearance, and 41 miles at disappearance. But if the observation at 

 Hawkhurst is correct, the meteor probably moved at an elevation of not more 

 than 50 or 55 miles at first appearance and 30 or 35 miles at disappearance. 

 From the former observations the length of its visible path was 90 miles ; but 

 in the latter case it woiild not exceed 70 miles ; and if the observations at York 

 and Hawkhurst only are employed, as affording the widest parallax, it would 

 be somewhat less. The duration of its flight was probably underestimated at 

 York at half a second, and overestimated at Wisbeach at 3 seconds. The ave- 

 rage duration is 1| second, giving the probable velocity of the meteor not more 

 than 40 miles per second ; while the actual velocity of the LyraVds, calculated 

 from the astronomical theory of the great April meteor-group, is 30 miles per 

 second. The recorded paths of this member of the shower diverged very ex- 

 actly from a common radiant-point between it and 6 Herculis, aboiit 20° from 

 the usually observed centre of divergence of the meteor-group in Lyra. 



The estimated height of a bright meteor seen on the 31st of August last 

 was also obtained from accordant observations of its apparent path at Boss 



