Jan. 5. 18S3 ] 



KNOWI.EDGE • 



13 



BRIGHT STAU XEAR THE SUX. 



[C75]— With reference to the phenomenon mentioned on p. -189 

 of Knowledge, as havinpr been seen on Dee. 21, if the object was 

 not a comet near perihelion, it was probably a temporary star. I 

 find tliero is no bright star near the place, the nearest being t and it 

 Sagittarii (of the 2ud mag.), each about 12° distant; bnt these 

 would be south of the sun, and not " a little above the sun's path," 

 lis the description states, besides being quite too faint to bo visible 

 ill the daytime (to the naked eye) under any circumstances. The 

 object could not have been the planet Venus, which was situated 

 about 23° west of the sun on the day in question. It seems worthy 

 of remark that the place of Kepler's celebrated " Nova," of 1G04, 

 was — at the time of observation — only about 8\° to the west (and 

 !i little north) of the sun's place. So that, if the object was really 

 a star, it seems possible that it may have been another outburst of 

 Kepler's star. The morning sky should be examined, as, if tlic 

 object be still visible, of the same brilliancy, it should now be a 

 conspicuous object before sunrise. J. E. GouE. 



Hallisodare, Co. Sligo, Dfc. 30, 1882. 



THE AURORA BOEEALIS.— THE RAIX-BAXD SPECTltO- 

 SCOPE. " 



[676] — I think there can be no doubt in regard to the connec- 

 tion between the " torpedo-shaped," " cometary," or " herring- 

 without-prico body " that was seen on Friday, Nov. 17, at 6.5 p.m., 

 .•ind the aurora, as the spectroscopic examination gave the same 

 bright line for both ; and this was situated between D and E in the 

 .spectrum, bnt nearer the former. Upon a previous occasion, when 

 observing the aurora of Oct. 2, I noticed a bright line in a similar 

 position, and for a few minutes only three distinct bright lines in 

 the red end of the spectrum. By-the-by, since sending those hints 

 about the use of the rain-band spectroscope, that appeared in No. 53 

 of your valuable periodical, I have made the discovery that with 

 small looking-glasses, placed at suitable angles outside the window, 

 the light can be reflected, apparently with very little loss, into the 

 room, and then examined with the spectroscope for percentage of 

 rain-band. For zenith observations this plan will be found ex- 

 tremely useful, and moreover enables an observer to examine the 

 U'reater part of the sky in any weather, without straining to look 

 round comers, or having to go outside the house. I do not know 

 whether you will consider this worth mentioning in Knowledge, 

 but I have certainly found it in practice of great assistance in the 

 •spectroscopic examination of the air. I". W. Cory, F.M.S. 



Buckhurst Hill, Essex, Xov. 30. 



TRANSIT OF VENUS. 



[077] — The day of the transit was most unpromising. Heavy 

 showers fell early in the morning, and during the day the sky was 

 ♦lotted with Heecy clouds which were continually crossing the sun 

 and impairing definition. I took up my position at the telescope 

 several minutes before external contact ; but, on account of the 

 clouds, I did not see the planet on the sun's disc until more 

 than a minute after external contact had taken place. As 

 Venus advanced on the limb of the sun, I had to be continually 

 sliifting the tinted wedge in order to keep the field of a 

 constant brightness. When the planet had advanced about 

 th>-ee-qnarters on to the sun, iho brightness increased rather 

 suddenly, and I saw the outer limb of Venus surrounded with a 

 beautiful halo of white light. At the same time the cusps appeared 

 to bo slightly blunted and bent outwards. As interior contact 

 ;i!i|>roached, the sun cleared, and, in a moment of good definition, 

 I .saw geometrical contact at 15h. 24m. 393s., Barbados sidereal 

 time. Immediately after this clouds passed, and it was impossible 

 to say at what instant the connection was severed. Mr. Talmage, 

 who is the other observer here, was more fortunate, and observed 

 the actual moment of separation free from clouds. He gives the 

 tlineat 15h. 21m. 43'8s. Barbados sidereal time. 



At Egress the sky was clearer, and I was able to observe the 

 time when the first shadow formed between the limbs, which 

 was 20h. 50m. 39'6s. Barbados sidereal time, and tlic time when the 

 ligament became as dark as the disc of the planet, which was also 

 the time of geometrical contact, namely, 20h. 50m. 53C3. B.S.T. 

 Mr. Talmage's observation for the latter phase was 20h. 50m. SO'ls. 

 li.S.T. The same phenomena were obscr\cd at egress as at ingress, 

 only the halo did not extend completely round tlie planet. It ex- 

 tended very much further on the north side of the limb than on the 

 south. The blunting of the cusps was not quite so marked. Ex- 

 terior contact was very good. My time was 21h. 11m. 30-Gs. B.S.T. 

 Mr. Talmage gives 21h. 11m. 261s. B.S.T., but does not consider 

 his observation very good. The discrepancies between our obser- 

 vations may seem large to those who have not seen the transit, but 



it must be remembered tliat the motion of Venus is very slow, and 

 that the phases are by no moans instantaneous. I believe that the 

 times are largely affected by the brightness of field employed, and 

 it is imi)ossible to obtain exactly the same brightness for different 

 observers. I saw no satellite, though I searched for one at intervals 

 throughout the whole transit. 1 employed a six-inch equatorial by 

 Simms, and Mr. Talmage employed cue of a similar aperture by 

 Dollond. The glass of the latter is about the best of its size which 

 I have seen. J. U. Thomson, Lt. R.A. 



Barbados, Dec. 6, 1882. 



THE DIAL OF AUAZ. 



[678] — In two church lessons, the second (or fourth) Book of 

 Kings, c. XX. and Isaiah, e. xxxviii., a perfectly unique "sign" is 

 described as given to llczekiah in his sickness, when he had inquired 

 " What shall be the sign that the Lord will heal me, and that 1 

 shall go up into the house of the Lord the third day.'" It is also 

 very briefiy mentioned in 2 Chronicles, c. xxxii. v. 24, as a well- 

 known event, with the further information that Merodach-Baladan's 

 embassy, which both accounts record soon after, came to inquire 

 (among other things) about " the wonder that was done in the 

 land." 



In the fullest account and first as they now stand, wliich I find to 

 be also the most accurate, and, doubtless, earlie.st, we find the sick 

 monarch offered this choice : — " Shall the shadow go forward ten 

 degrees, or go back ten degrees? " The advance or recession, which- 

 ever he chose, were plainly to be of one identical angular measure, 

 pre-announced, and which was some aliquot part of either a quad- 

 rant or the semi-diurnal arc, whichever the diallers of that time 

 used to divide. " And Hezekiah answered. It is a light thing for 

 the shadow to go down ten degrees ; nay, but let the shadow return 

 backward ten degrees." He evidently thought, before seeing either, 

 that the return would be the more marvellous ; but, in fact, cither 

 the sudden shifting back or sudden advance are equally strange and 

 out of human power ; indeed, so uncommon are both phenomena 

 that I should be rather more surprised if the records of any Obser- 

 vatory or Royal Society kept for 1,000 or oven 5,000 years, related 

 a single instance than at their relating none. 



Happening to know, however, of an afternoon some years ago 

 in which both did certainly occur, I have thought that possibly 

 some reader of Knowledge may have witnessed, and can describe 

 the facts. There are plenty of sun-dials in southern England 

 whereon I know (bnt did not till years after the occurrence) that 

 the "wonder" was repeated exactly as Isaiah described — I mean 

 in the earlier and fuller account, vol in our present " Book of 

 Isaiah." If none happened to see the shadow shift, 1 shall willingly 

 explain how I know that both the signs offered were certainly that 

 day visible. E. L. G.\rbett. 



[I should feel greatly obliged if Mr. Garbett would describe the 

 phenomena he observed, and give his interpretation of it. — E. P.] 



ELECTRICITY IN DENTISTRY. 



[679] — It is a fact that electricity has been tried as a means of 

 deadening the pain during tooth extraction. Mr. Snape, of Liver- 

 pool, was, I believe, the dentist who brought the system most 

 prominently forward, and adopted it in his oivn practice with some 

 success. It was found, however, in many cases that the pain 

 occasioned by the shock was greater than that of the simple 

 operation. The system therefore met with but little favour, and 

 though one, at least, of the manufacturers of dental appliances 

 included the battery and insulated forceps in his catalogue, there 

 are probably very few indeed in the profession who have tried it. 

 My own idea is that it might be applicable in the extraction of 

 (h'ad teeth, i.e., teeth in which the nerves are dead ; bnt where the 

 pulp or nerve is living, the shock would doubtless be excruciating. 



We find for the same reason that the local application of cether 

 is not practicable except in the extraction of dead teeth and stumps. 

 John Teude Fhipp, L.D.S.I. 



LUMINOUS PAINT. 

 [6*0] — It strikes me there is an error in the article on "Lumi- 

 nous P.aint," where it states that " the light given off will not 

 affect the most sensitive photographic plates." The fact that it 

 is very largely used by photographers as a standard light to test 

 photographic gelatine plates cannot be known to the writer. 



Alexander Cowan. 



CORSET WEARING. 

 [6S1] — Where " E. H." remarks that there is about three times 

 as much breathing-space in the lungs as is needed for ordinary 



