March 14, 1901] 



NATURE 



471 



accompanied by W. H. Julius and W. H. Wilterdinck, 

 of Leiden, and will probably make Padang his head- 

 quarters. Somewhere in the neighbourhood of Padang, 

 also, the American astronomers. Prof. Barnard and Prof. 

 Todd, together with a party from the Washington 

 Observatory, and another party from the Lick Obser- 

 vatory, are expected to set up their instruments. Prof. 

 Campbell has selected Mr. C. D. Perrine to take charge 

 of the expedition from the Lick Observatory, and this 

 observer will be accompanied by Mr. R. E. Curtiss, of the 

 Observatory at Berkeley ; the expenses of the expedition 

 will be defrayed by the well-known liberal benefactor to 

 science, Mr. W. H. Crocker, of San Francisco. The 

 Obsetvatory has further learned, through Father Cortie, 

 that certain members of the Calcutta Jesuit Mission will 

 also go to Padang to observe the eclipse. 



The most direct route to Padang from Europe is by 

 the Rotterdam-Lloyd line of steamers ; a steamer leaving 

 Southampton on .^pril 9 and Marseilles on April 18 is 

 due at Padang on May 12, and there is a return steamer 

 on May 24, due at Marseilles on June 18. Return tickets 

 at greatly reduced rates may be obtained through the 

 British Astronomical Association. 



As to the work to be undertaken, the great duration of 

 totality emphatically demands that almost every effort 

 should be directed towards the corona. Indeed, the study 

 of the chromosphere and prominences during eclipses 

 may well be considered to have reached a halting-place, 

 so that in any case the study of these appendages 

 would be considered of secondary importance. The 

 great success which has attended the observation of 

 recent eclipses has in some degree placed observation 

 ahead of solar theory, and it is perhaps for this reason 

 that most of the observations which, we understand, are 

 to be undertaken are along familiar lines. To a certain 

 extent this is, of course, inevitable, for it is always rightly 

 regarded as a prime duty to record the phenomena as 

 completely as possible. 



Adequate provision is made for securing pictorial 

 records of the corona. Some of these will be on a large 

 scale to show the finer details of the lower reaches, and 

 others on a smaller scale to depict the extensions seen 

 with the naked eye. Messrs. Maunder and Claxton will 

 utilise the photoheliograph of the Mauritius Observatory, 

 giving pictures of the sun nearly 8 inches in diameter, 

 and in addition will be provided with a 4-inch corona- 

 graph fitted with a negative enlarging lens to give 

 images 2 inches in diameter ; the long extensions will be 

 specially attacked with a 4-inch Dallmeyer R.R. lens of 

 32 inches focus. 



At Padang, Mr. Dyson will erect the Thompson photo- 

 heliograph of 9 inches aperture, which was successfully 

 employed by the Astronomer Royal in India and 

 Portugal, the photographs being enlarged by a magnifier 

 to a scale of 4 inches to the sun's diameter. The same 

 observer will also take charge of a double camera with 

 4-inch lenses of relatively short focus to grasp the feeble 

 rays of the longer streamers. 



It is probable that Prof. Barnard's instrument will be 

 the coronagraph of 61 feet focus, with which he obtained 

 such admirable photographs of the prominences and 

 inner corona last May. Prof. Todd will again employ 

 his wholesale method of obtaining photographs with 

 cameras in which the exposures are given and plates 

 changed automatically. Coronagraphs of 33 feet 3 inches 

 and 5 -feet focus will form part of the equipment of the 

 Jesuit Mission. 



For the spectroscopic records, Mr. Maunder is pro- 

 vided with the 2-inch prismatic camera with which Mr. 

 Evershed secured valuable photographs during the 

 eclipse of 1898. With this type of instrument, the 

 prmciples of which are now sufficiently familiar to render 

 a description superfluous, the spectra of both corona and 



NO. 1637, VOL. 63] 



chromosphere are recorded in the most complete manner. 

 A modified prismatic camera, in the form of an objective 

 grating, will be employed by Mr. Newall in an attempt 

 to photograph the coronal rings. Mr. Dyson will again 

 employ the two slit spectroscopes belonging to Captain 

 Hills, which were used in India and Portugal, one of 

 them being specially adapted for the ultra-violet spec- 

 trum. Another important spectroscope will be the 

 prismatic camera forming part of I>r. Nyland's equip- 

 ment ; this consists of a 6-inch objective and two prisms 

 of 45°, thus duplicating one of the instruments employed 

 in the last two eclipses by Sir Norman Lockyer. The 

 Jesuit Mission will investigate the spectroscopic 

 phenomena with a Rowland concave grating of 36 inches 

 focus, and a prismatic camera of 33 inches focus. 



In the case of the slit spectroscopes and the objective 

 grating, the long duration of totality will obviously be an 

 immense advantage, and it is very desirable also that the 

 experiment of giving very long exposures with the prism- 

 atic cameras should be made. 



Among the more special inquiries, Mr. Newall wil) 

 again attempt to investigate the rotation of the corona, 

 and also to obtain photographs of the corona in polarised 

 light. The first of these observations is a particularly 

 delicate one, depending for its success on photographic- 

 ally recording the coronal spectrum with sufficient dis- 

 persion to exhibit the minute displacements of the bright 

 lines produced by the rotation. The long duration of 

 totality is especially favourable for this observation, but, 

 on the other hand, there is evidence that at the time of 

 sun-spot minimum the coronal lines are of but feeble in- 

 tensity. Success is therefore by no means assured, but 

 the slit spectroscope to be employed in the experiment is 

 one of great efficiency and convenience, and the attempt 

 is well worth making. 



The study of the polarisation of the coronal light is also 

 of some importance. The luminosity of the corona, 

 apart from that due to the luminous gases of the inner 

 corona, has been ascribed to the reflection of solar light 

 by the small particles of which it is supposed to consist, 

 and to the direct emission of light by such particles ren- 

 dered incandescent by solar radiation. The bolometric 

 observations of Prof Langley's party at the last eclipse, 

 however, led to the conclusion that the corona appears 

 " neither to reflect much light from the sun, nor, chiefly 

 by virtue of a high temperature, to give light of its own, 

 but seems rather to be giving light in a manner not asso- 

 ciated with high temperature" (NATURE, vol. Ixiii. p. 67). 

 On the other hand, Mr. Newall, during the same eclipse, 

 found a marked polarisation of the coronal light, indi- 

 cating that a considerable proportion of the light is re- 

 flected. The accumulation of additional data bearing on 

 the origin of the light of the corona, therefore, seems very 

 desirable. 



The fact that a British man-of-war will be sent to 

 Padang to render assistance to Messrs. Dyson and 

 Newall is a sufficient guarantee that an adequate record 

 of the general phenomena of the eclipse will be made. 



A. Fowler, 



RED RAIN. 



AN unusual, though it can scarcely be called a rare, 

 meteorological phenomenon is reported from Italy, 

 and has been made the subject of much highly coloured 

 descriptive writing in the daily Press. The plain facts 

 are thus given by Reuter's correspondent in Palermo in 

 a telegram dated March 10 : 



" Since last night a dense lurid cloud has hung over 

 this town. The sky appears of a sinister blood red hue, 

 and a strong south wind is blowing. The drops of rain 



