5o8 



NATURE 



[April 12, 1877 



doubtless a slip, but in the particular reaction described 

 is of some importance. 



We feel sure that Mr, Crookes will receive the thanks 

 of those interested in this subject in England for the care 

 and completeness with which he has arranged and carried 

 out the text-book, 



OUR BOOK SHELF 



Half-Hours mnong some English Antiquities. By 

 Llewellynn Jewitt, F.S.A., &c. (London : Hardwicke 

 and Bogue, 1877.) 

 This ought to be an extremely useful little manual to 

 those who desire to obtain a knowledge of the various 

 classes of antiquities to be found in England, both pre- 

 historic and historic. Mr. Jewitt writes with full know- 

 ledge and in a manner that cannot fail to secure the 

 attention of the reader. He theorises very little, confin- 

 ing himself mainly to a statement of facts in reference to 

 the various objects included under the name of antiquities. 

 He speaks of barrows, stone-circles, cromlechs, flint and 

 stone implements, bronze instruments, Roman remains of 

 various kinds, ancient pottery, arms and armour, sepul- 

 chral slabs and brasses, coins, church bells, glass, tiles, 

 tapestry, personal ornaments. Thus, it will be seen, Mr. 

 Jewitt's programme is extensive and varied, and although 

 much cannot be said in the space at his command, his 

 little work will prove a very useful introduction to works 

 of a more special kind. Not its least valuable features 

 are the illustrations — upwards of 300 — which accompany 

 the text. 



LETTERS TO THE EDITOR 



\The Editor does not hold himself responsible for opijiions expressed 

 by his correspondents. A^either can he undertake to return, 

 or to correspond viith the ivriters of, refected nianusciipts. 

 No notice is taken of anonymous communications.'^ 



Centralism in Spectroscopy 



In Nature, vol. xv. p. 489, there are some remarkable 

 counter-assertions by Mr. Christie to certain of my matter-of- 

 fact statements on your p. 449, of which the most pressing for 

 me to notice is the paragraph wherein he declares that " the 

 Edinburgh Observatory has, for the \2&t four years, possessed 

 three spectroscopes which are almost precisely identical with 

 those used with such effect by Dr. Huggins." 



I beg to say that the above is not the case, and for this, 

 amongst other reasons, viz., that though three spectroscopes are 

 there in part, they belong solely as yet to H. M. Office of Works 

 in London, which office, moreover, decided long since to return 

 all of them to their maker, in lieu of ^«(?new spectroscope. And 

 Mr. Christie must have known of this perfectly well when he 

 wrote the above paragraph, for the carpenters of the department, 

 who fetched away, about nine months ago, the one and only colli- 

 mator to all those three partial spectroscopes, in order to send it 

 back to its maker, spoke, as a matter of notoriety, of Mr. 

 Christie himself being the adviser of H.M. Office of Works in 

 that transaction, as well as the designer of the one new spectro- 

 scope ordered by the London office to take the place of the 

 former three, but not received here yet. 



With regard to the other new, and far more important, 

 Greenwich spectroscope, of which Mr. Christie both chides me 

 for not waiting for the full account to appear, as he now inti- 

 mates, in a forthcoming number of the Proceedings of the Royal 

 Society, and also challenges me to discuss its principles with 

 him at once, I beg to say that my former remarks had reference 

 solely to the official codex of last year's work at the Royal Ob- 

 servatory, Greenwich, as published by the Royal Astronomical 

 Society in their last Anniversary Report, at p. 162, where all the 

 world both may, and I suppose was intended to, see it, and where 

 Mr. Christie's name appears no more than it did in my letter. 

 And as in that letter (at your page 450) I ventured to assign 

 the next anniversary meeting of the same society as the limit of 

 time within which the full practical value of the said new Green- 

 wich spectroscope will have been arrived at, I do not think we 

 can do better than wait for that time to arrive. 



15, Royal Terrace, Edinburgh, April 6 PiAZZi Smyth 



Parhelia and Paraselense seen on March 20, 1877, and 

 again on March 21, 1877, at Highfield House Obser- 

 vatory 



Perhaps this phenomenon is the most remarkable of the 

 many somewhat similar ones that it has been my good fortune 

 to witness during the last forty years, the chief features being 

 brilliancy and persistency. 



Fig. I represents the appearance at 8 a.m. : an ordinary halo 

 of 22^" radius, with an elongated mock sun at the apex. This 



lasted till 9.30 A.M., when, in addition to the halo, o )8, and the 

 mock sun, 7, there was a second circle, S e, of 45° radius, also 

 having the true sun for its centre, an inverted portion of a third 

 circle, t) d, of 22|" radius having its centre 45° above the true 

 sun ; also a portion of a fourth circle, t k, of 90° radius, whose 

 centre was 90" below the sun. The mock sun, 7, was very bright 

 and prismatic, as also was the circle, a yS. The other rings were 

 colourless. 



a Sim, fi* 



Fig. 2. — 9.30 A.M. 



At 9.40 A.M. the portions of circles t] and lk had vanished, 

 but a wing-like portion was now visible, and brilliant (see Fig. 3, 1 

 A co). This remained until 11. 15 a.m., when only afi and the 

 mock sun 7 remained, lasting all the morning. At 12.57 P-M- 

 the arc, ik, again appeared, and was visible until 1.22 p.m., the 

 halo, a 3, and the mock sun, 7, lasting till 5 P. M. 



At 7.40 P.M. an ordinary lunar halo (o3, Fig. 5), and atl 

 8.25 P.M. a portion of a second circle, Se, of 45° radius, and of I 

 a third circle, i k (of 90° radius) and an elongated mock moon, 7, \ 



Fig. 3.; 



were very apparent. At (8.31 the ordinary lunar halo a\ 

 remained. At 9.10 a portion of a circle, v 0, not quite- 

 radius, appeared (see Fig. 6), but this did not touch tiie cii 

 a/3, but was 10" above it. At 9.15 p.m. this also vanished, 

 the lunar halo remained as long as the moon was above tl^| 

 horizon. 



On March 21, at 8 a.m., there was a solar halo aa4| 

 mock sun exactly like the one seen at 8 A.M., March 20 (s6e| 



