OCTOBBR. 1901.] 



KNOWLEDGE. 



22.5 



resemblance been enhanced by an aocidcnt-al growth of 

 algje. 



As regards the manner in whitli tho growth of algne 

 is maint-aiuetl in the sloths from one generation to 

 another, the only rational explanation which presents 

 itself is that, the young sloths become infected with 

 alga-spores from their parents. As already mentioned. 

 Dr. Ridewood has pointed out that in very voung 

 individuals of the two-toed sloth a large proportion of 

 the hairs are devoid of grooves; and it would therefore 

 seem that the young sloths do not develop a growth of 

 alga till about the time they are old enough to leave 

 the maternal arms and hang independently on the leafy 

 .ind lichen-clad boughs of their native foixsts. 



THE TOTAL SOLAR ECLIPSE OF MAY 18, 1901. 



By E. W.\I.TER Jf.WS'DER, F.R.A.S. 



The striking success which attended the observations 

 of the eclipses of 1898 and 1900 has gone far to make 

 people forget that conditions so favourable are very 

 rai-ely obt^iined. On both occasions we had the shadow 

 track passing for an immense distance through settled 

 and civilized countries easily reached from abroad, and 

 where all necessaries and conveniences could be readily 

 procured. On both occasions, too, a great number of 

 expeditions were organized, and many obscr\'ing stations 

 occupied, and evei-yone, without exception, enjoyed fine 

 weather. This must be regarded as most phenomenal 

 good fortune, which it was again.st every probability 

 would be soon repeated. There is therefore no need to 

 feel disappointed that the same unusual degree of 

 success did not attend tho eclipse of last May. It was 

 one of specially long duration, but its geographical con- 

 ditions were of the tantalizing character which are 

 almost inseparable from such. The shadow track lay 

 near the equatoi-, and this being so, it was inevitable 

 that much of it should lie across the open ocean or 

 countries neither accessible nor civilized. Broadly 

 speaking, only two limited regions were sufficiently 

 accessible to tempt astronomers. For the eclipse at 

 morning, the islands of Bourbon and Mauritius were 

 available; whilst the west coast of Sumatra had it in 

 the early afternoon. A French expedition, under M. 

 Deslandres, went to Bourbon; whilst Mrs. Maunder and 

 myself went to Mauritius. But the chief stream of 

 observers flowed to Sumatra, attracted, no doubt, by the 

 unusual length of totality there ; and some eight or ten 

 distinct expeditions, English, American, Dutch and 

 Japanese took up their stations at Padang or within a 

 few miles of it. 



This limitation of observation to two very restricted 

 areas stands in great contrast to the experiences of 

 1898 and 1900; but it cannot be doubted that it was 

 imposed upon astronomers by the conditions of the 

 case, and a similar limitation has been found imperative 

 in the majority of eclipses. 



As I have not yet had the opportunity, since my 

 very recent return to England, of leaining much as to 

 the details of the results obtained by the numerous 

 parties in Sumatra, I must restrict my present account 

 entirely to the Mauritius observations. 



From its situation, far out in the Indian Ocean, and 

 nearly under the Tropic of Capricorn, Mauritius is in 

 an extremely favourable position for the study of the 

 great movements of the atmosphere. To the north of 

 the island lies the equatorial belt of calms, with its hot. 

 damp and rarefied atmosphere; to the south, tropical 



calms characterized by their cool dry atmosphere and 

 high bai'ometric pressure. These two belts do not re- 

 main in a h.^ced position but move northward or sovith- 

 ward with the sun. Mauritius therefore comes at one 

 time of the year into tho one belt, and si.K months later 

 into the other, whilst for the greater part of tho year 

 the island lies in the track of tlie south-east trade winds. 

 During the period that the sun is vertical, or nearly so, 

 over the island, there is a liability to fierce cyclonic 

 disturbance, the actual centre of which may or may not 

 pass over the island, but the passage of which may make 

 itself sensible even at the distance of luuidrcds of miles. 

 Further, beside tho observations which can be made on 

 tho island itself, it stands in the great highway fiom 

 tho Cape of Good Hope to India, a highway which was 

 for long the chief route from England to India. It 

 therefore was, and still is to some extent, a place of 

 call for a largo proportion of the vessels navigating the 

 Indian Ocean, and the logs of the ships putting in heie 

 afford the means for ascertaining tho general state of 

 tho weather over the entire ocean. 



This favourable position drew the attention of a 

 traveller, Mr. C. Meldrum, who half a century ago had 

 the misfortune to be wrecked on Mauritius cm a voyage 

 from India to the Cape. Frmn this Hiiic lie made the 



jrjtj I, — Koval Alfred Observatory, irauritiiis. Tin- group of trees 

 on the left-haiid siilo of the picture hiul to be cut ilowu to a lieiglit of 

 10 feet iu order to give a lAoar view of the l')elip9e. 



island his home, and the study of the atmospheric dis- 

 turbances of the Indian Ocean his life work. He 

 founded the Meteorological Society of Mauritius in 

 1853, and was for many years its secretary; he collected 

 and copied the logs of as many of the vessels as called 

 at Mam-itius as he could obtain; he procured tho 

 establishment, first of a modest meteorological obser- 

 vatory in Port Louis, the capital, and later, as the value 

 of his researches became better known and more 

 appreciated, of a larger and more comi)lotely fitted one 

 at Pamplemousses, some seven miles to the north. The 

 foundation stone of this new institution was laid by 

 H.R.H. Prince Alfred, Duke of Edinburgh, during his 

 visit to the island in 1871, and it still bears his name. 



The selection of Pamplemousses as the site of the new 

 observatory has proved a most unfortunate one. This 

 could not have been foreseen at the time when the 

 erection of the observatory was resolved upon. 

 Mauritius was then, except for a few sporadic cases, 

 quite free from malarial fever, and the broad level plain 



