May II, 1893] 



NATURE 



41 



The instrument was provided with two object glasses of 4-inch 

 aperture, the tube carrying them having a partition down the 

 middle. The image formed by one of the lenses was received 

 directly on the photographic plate, but in the other case it was 

 magnified about three times by one of Mr. Dallmeyer's new 

 telephotographic lenses. The dark slides carrying the photo- 

 graphic plates were ingeniously arranged so that by a single 

 operation two plate? were exposed. Lieutenant Hills, R. E., 

 one of the volunteer observer! was in charge of two spectro- 

 scopes of the ordinary form provided 'vith slits. These were 

 mounted on an equatorial stand, and were each provided with 

 a 3-inch condensing lens. Here, again, photographic plates 

 replaced the eye. A piece of apparatus for determining the 

 total light of the corona was in the hands of Mr. Forbes, the 

 other volunteer observer. Lieut. -Commander Lang undertook 

 to make a drawing of the faint outlying parts of the corona by 

 following the plan initiated by the American astronomer New- 

 combe in 1878. This consists in erecting a wooden disc in line 

 with the eye and the eclipsed sun, and at such a distance that it 

 appears to cover all the bright inner corona. The eclipse itself 

 is thus eclipsed, and the observer has an opportunity of studying 

 the more delicate parts of the corona, his eye being protected 

 from the brighter light by the wooden disc. 



The weather, fortunately, was magnificent during the whole 

 tay of the observers at Fundium, and almost cloudless skies 

 were experienced both day and night. By April 10 the instru- 

 ment* had all been Carefully erected and adjusted by observa- 

 tions of the st«is, and all was in readiness for the eclipse. 

 Reheirsals of the operations which were to be gone through 

 during the eclipse were now begun, and continued daily. It 

 \ras arranged that the commencement of totality should be an- 

 jjou.iced by pistol shot. Prof. Thorpe giving the signal to fire. 

 Quartermaster Hallet was then to record in a loud voice the 

 lapse of the 250 seconds of totality by reading the 15 seconds 

 sandglass, which is so commonly used with the ship's log. 

 Several rehearsals were gone through at dusk, when it was 

 estimated that the light was about equal to that which might be 

 expected during totality. 



At last the day of the eclipse arrived, and everything was in 

 complete order. The morning was a little more hazy than 

 «3ual, but all felt confident of obtaining at least a moderate view 

 of the eclipse. The observers themselves were at their posts 

 soon after noon, and driving clocks and other details were 

 attended to. At five minutes past one the moon was seen to 

 have encroached on the south-western limb of the sun, and as 

 it gradually passed over the disc the temperature of the air as 

 gradually fell. At two o'clock the officers of the Alecto, who 

 were kindly assisting the observers, also took their places. The 

 light now waned very rapidly, and the breeze felt cold. In 

 appearance the light of day at these stages very much resembled 

 that which precedes an English thunderstorm. All the ob- 

 servers were now in perfect readiness for the pistol shot. "Five 

 minutes" was announced by Prof. Thorpe, and I began my 

 spectrum photographs, exposing six plates before totality. 

 Amidst almost breathless silence the sound of the pistol shot 

 was awaited. Eventually a similar pistol signal adopted in the ' 

 French camp was clearly heard, and that moment the shadow of 

 the moon went sweeping past. Prof. Thorpe's signal to fire, 

 however, was not given until at least 10 seconds later. As the last 

 trace of bright sunlight disappeared out flashed a magnificent 

 -corona of silvery light, together with numerous red and white 

 prominences. 'The corona was very evenly distributed round 

 the dark moon, that is to say, there were none of the great 

 extensions along the Equator which were seen in 1878 and 1889. 

 The light of the corona was very bright, and the lamps which 

 had been provided for the use of the observers during totality 

 were quite unnecessary — indeed, the sky light was so bright 

 that no stars became visible at all, but Jupiter and Venus, 

 which happened to be quite near the sun, shone out most dis- 

 tinctly. At Bathurst, however, the sky appears to have been 

 clearer, and some of the brighter stars were also seen. The 

 various observations were made and the photographs taken with 

 no hitch whatever beyond the loss of about 10 seconds at the 

 beginning of totality. This caused me to. lose three exposures 

 during totality, and reduced the number of Sergeant Kearney's 

 photographs from 12 to 10. To err on the right side, Lieutenant 

 Hills very fortunately closed his dark slides soon after "25 

 seconds" had been called by the quartermaster. In this case 



I 



he slightest flash of sunlight would have been disastrous, 

 i'ive minutes after totality was over I exposed my last plate, 



NO. 1228, VOL. 48] 



and the actual work of the expedition was at an end. What 

 was more, all were confident of success. 



Now, as to the results of the observations and photographs. 

 Though it is much too early to attempt to state all that we may, 

 except to learn from them, one point is clear. The general 

 distribution of the corona is exactly what was expected, seeing 

 that the sun is now in a very disturbed state. The sun spots, it 

 is well known, have an eleven yearly period, and at the present 

 time they are nearly at a maximum. "This, in fact, made the recent 

 eclipse one of the highest importance. It has been observed in pre- 

 vious eclipses that when the spots are at a minimum the corona is 

 very much extendcdinthedirection of the sun's equator, while, on 

 the other hand, when the spots are at a maximum the corona is 

 very much more evenly distributed. This supposed periodicity of 

 the general form of the corona has received further confirmation 

 by the recent observations. No unusual equatorial extension is 

 shown on the excellent photographs taken by Sergeant Kearney, 

 and none was observed by Lieut. -Commander Lang, who was 

 specially looking for it. At Prof. Thorpe's suggestion Dr. Prout, 

 the colonial surgeon at Bathurst, also erected a similar wooden 

 disc, and his observations confirm those of Captain Lang. The 

 prominences also follow the sun spots with regard to frequency, 

 and, as already stated, a large number of them were seen. 

 These are shown on Sergeant Kearney's photographs, and a 

 complete record of the spectrum of each one is shown on the 

 photographs taken by myself. The latter have the further ad- 

 vantage of showing the forms of the prominences as well as the 

 spectra. Some of them chiefly show lines of hydrogen and 

 calcium, while others again are almost crowded with lines of 

 various metals. A complete record of the prominences has 

 therefore been secured. With regard to the spectrum of the 

 corona it seems doubtful at present Whether our knowledge 

 has made any great advance by the recent observations. The 

 spectrum appears to have been very largely continuous, such as 

 would be given by a mass of incandescent solid particles. One 

 green line, which has previously been observed to be very 

 prominent in the coronal spectrum, and the bright yellow line 

 of the unknown substance, which is called helium, however, are 

 shown in my photographs, and subsequent detailed examination 

 may lead to the discovery of others. Lieut. Hill's photographs, 

 which were specially exposed for the coronal spectrum, show a 

 large proportion of continuous spectrum, and several lines which 

 require further investigation. Much is to be hoped for, how- 

 ever, in another direction. The question of the constitution of 

 the layers of the vapour which lie closest to the photo- 

 sphere is one of the first importance to solar physicists. 

 I had made arrangements to take two successive instan- 

 taneous spectrum photos as nearly as possible after the 

 commencement of totality, but, as already stated, the oppor- 

 tunity was lost by reason of the lateness of the signal. The 

 photos taken immediately after totality, however, promise to 

 throw considerable light on the subject. Only two of these 

 have been developed at present, and in addition to the ordinary 

 spectrum of the uneclipsed part of the sun, they show large 

 numbers of bright lines in the spectrum of those portions of the 

 sun's atmosphere which were still left exposed by the moon. 

 These, of course, also require a very detailed examination before 

 any conclusion can be drawn. Of the thirty plates which I ex- 

 posed only eleven have been developed so far, the facilities at 

 Fundium not being very great. These were selected here and 

 there from the whole series, and little doubt is entertained as to 

 the good quality of the remaining plates. The photographic 

 work was undertaken with the view of investigating the laws of 

 variation in the brightness of the corona (i) according to the 

 distance from the photosphere ; (2) from one eclipse to another. 

 Prof. Thorpe and Mr. Gray were successful in securing obser- 

 vations of the intensity of the light at sixteen different points of 

 the corona, while Mr. Forbes made eleven measurements of the 

 total light at as many different stages of the eclipse. All these 

 observations were considered to be of a high degree of accuracy, 

 but reduction to former standards and comparisons with measures 

 at former eclipses have still to be made. 



M. Deslandres' equipment consisted chiefly of spectroscopes 

 of various forms, but in addition he was provided with instru- 

 ments for photographing the eclipsed sun, one on a large and the 

 other on a small scale. The haze somewhat interfered with his 

 work, but he appears to have been fairly successful with such 

 plates as were developed before the British expedition left. 



The natives at Fundium were by no means alarmed during 

 the eclipse, and there was fortunately no call for the guard of 



