Nov. 17, 1887] 



NA TURE 



69 



probably the finest in the world. Here are found the Oriental 

 sapphire, ruby, and emerald, in perfection. 



Topaz has recently been found at Pike's Peak, Colorado, in 

 large quantity. Some masses weighed 2 pounds each ; and very 

 fine clear white stones have been cut, weighing from 125 to 

 193 carats. 



Among ornamental stones should be mentioned a very beauti- 

 ful variety of serpentine from Maryland, called verd antique, 

 which is being largely used in the interior decorations of the 

 Philadelphia Court House. Another variety, resembling jade, is 

 the green williamsite from Pennsylvania. Alabaster of various 

 colours abounds in many localities ; and marbles, some as beauti- 

 ful as the Mexican onyx, are found in nearly every State. The 

 malachite and azurite, jet, and many other gems of minor im- 

 portance were briefly described. 



THE OCTOBER METEOR-SHOWER OF 1887. 



T^HE 'display of Orionids has been recently observed at this 

 station with greater success than has attended my eflfbrts 

 in any previous year. This shower has not, perhaps, exhibited 

 such richness as it did in 1877, but the present occasion has 

 been more favourable as regards the conditions ; the moon being 

 absent from the morning sky, and a period of tolerably clear 

 weather occurring just at the important time. 



In all, I numbered ninety Orionids between October 1 1 and 24, 

 and the radiant-point during this period exhibited a stationary 

 position amongst the stars. The shower has this year met with 

 rather a formidable rival in a bright display of forty-five meteors 

 from a radiant at 40° -t- 20" close to € Arietis. I have witnessed 

 the latter stream in several preceding years, though not in such 

 conspicuous strength, and have particularly referred to it in the 

 Monthly Notices, vol. xliv. , pp. 24-26, as furnishing many bright 

 lireballs at this season. 



It will be convenient to arrange my new observations in a 

 tabular form : — 



II nights 



46i 459 90 45 91° -f- 15° 



The 1 6th and 22nd were overcast, and on the 19th and 23rd 

 the observations were much obstructed by clouds. It is note- 

 worthy that I only recorded one Orionid on October 14 during a 

 watch of seven hours, though on the following night this shower 

 -.upplied seventeen meteors. 



The radiant-point of the October meteors has long been 

 accurately known. Prof. A. S. Herschel observed it with great 

 precision on October 18, 1864, and October 20, 1865, and 

 found the centre at 90° + 16°, and 90° -f 15° respectively, in 

 those years. All the best of later determinations have agreed 

 closely with these results, and it will be noticed that my value 

 for the present year, as given above, is nearly identical with them. 

 In further confirmation I may mention that Mr. David Booth, 

 of Leeds, observed more than sixty shooting-stars during a watch 

 of five hours, from lojh. to iSgh. on the night of October 20 

 last, and saw twenty-four Orionids which gave a sharply-defined 

 radiant at 90° -f 16°. 



One of the principal objects of my late observations was to 

 iscertain whether the radiant centre of this stream showed any 

 displacement of position on successive nights, and similar to that 

 affecting the Perseids of August — a peculiarity which I first 

 pointed out in Nature, vol. xvi. p. 362. But the radiant of 

 the Orionids has (when the small, unavoidable errors of observa- 

 tion are allowed for) quite failed to exhibit any change of place 

 relatively to the contiguous stars. It appeared to maintain an 



absolutely persistent position 1° north of the star { Orionis. My 

 observation on October 15 placed it at 91° -f 16°, and nine nights 

 later, viz. on October 24, I found the meteors were radiating 

 from exactly the same focus. In 1877 and 1879, October 15, I 

 derived the radiant at 92" + 15" and 93° -f 17°, and in 1878, 

 October 22, I fixed it at 92' + 14". A comparison of all these 

 values renders it sufficiently obvious that there is no visible 

 displacement in the position of the Orionid radiant during its 

 active display from October ii to October 24. And there is a 

 high degree of probability that the point is stationary during the 

 whole period of the shower's sustenance from about October 9 

 to October 29 ; but I have never secured many paths and been 

 enabled to get a good radiant near the limiting epochs of its 

 display, when it is extremely feeble, 



Mr. Booth, at Leeds, has been carefully observing numbers of 

 meteors during the past few months, and a searching comparison 

 of his results with those obtained at Bristol during the progress 

 of the Orionid shower has shown that several of the same 

 meteors were observed at both stations. Three of these are 

 typical members of the October display, whilst three others had 

 their origin in the minor systems which are so plentifully dis- 

 tributed over the sky at this season of the year. The computed 

 heights and p^ths of these six meteors are : — 



The three last in the list were Orionids, and they appear to 

 have been observed at somewhat greater elevations in the atmo- 

 sphere than is usual. The 4th magnitude meteor of October 20, 

 I ih. 45m., was no less than 106 miles high at its first appearance, 

 over a point near Eversham, Kent, and the two observations are 

 in perfect agreement in indicating these figures. The mean of 

 the three Orionids gives 96 miles for the beginning points and 

 68 for the ending, and the average radiant comes out at 

 87°+ 16°, which is 3° or 4" west of the usual position. But the 

 average values deduced from so small a number of instances 

 cannot have much weight as indicating accurately either the 

 heights or radiant of the general body of the meteors forming 

 this notable group. 



The Arietids, which have developed into an important shower 

 this year, traverse their paths with medium speed, and are rather 

 conspicuous meteors, without trains or streaks except in excep- 

 tional cases. As to the Orionids, they move swiftly, and are 

 accompanied in almost every instance with streaks. The latter 

 will sometimes brighten up considerably after the nuclei of the 

 meteors have died away. The more brilliant Orionids are fine 

 flashing meteors, leaving streaks which are occasionally very 

 durable. 



The contemporary showers of the October epoch, though 

 extremely abundant, are not marked by special activity, except 

 perhaps in the case of the Arietids, already referred to. This 

 year the following have been the best of the minor streams :— 



Date. 



Radiant. Meteors. Appearance. 



Of these the most pronounced is at 105° + 22°, near 8 

 Geminorum, which I also observed in 1877 and 1879. It has 

 also been recorded as a prominent stream by Zezioli and others, 

 and is identical with the Gemellids of Mr. Greg's catalogue 

 (1876). It is chiefly a morning shower ; its meteors are often 

 brilliant, and regularly display the phosphorescent streaks which 

 form so characteristic a feature of the Perseids, Orionids, and 

 Leonids. The shower in the head of Ursa Major at I35° + 68 

 is also an active one at this epoch ; I saw it in 1877 at 

 133° + 68", October 2-19, and these appear to be the only two 

 observations of it obtained hitherto. W. F. Denning. 



