June 9, 1910] 



NATURE 



441 



contents of the planetary atmosphere. The observations 

 of Beer and Madler, Secchi, Lockyer, Denning and others, 

 of apparent changes caused by clouds have been generally 

 accepted as strong evidence for the existence of the cloud- 

 producing compound of our own atmosphere. 



Turning now to the actual observations of features, and 

 their modifications, during the recent opposition, we find 



lO.Tuiff,/ -I'.MO JiJ,ii//./ 



'::: J.-Z/^f X-. iSi ' l^'.h.r, / 



X- I-*)' J2J^u ,l=irw»' 2-5Aoi;f 



V^»/»v«//v- A.18.< dOr/i,/.!^ X--\i.< nOrfoii-.- I- S.V WOrAol. 



f io. 2. ^..c».i^<;,- 11. i.ui, :>ijji,itni ^l^J\.\l Cap Oi Ma S. 



that the diminution and transfiguration of the southern 

 polar cap was recognised quite earlj' in the season. 



M. Jarry Desloges, obser\ing with a 29-cm. refractor 

 at Massegros (Lozere), recorded {Astronomische Nach- 

 richten. No. 4340) a dark cutting — shown on the first 

 drawing in Fig. 2 — in longitude 190° on June 20-23, and 

 at the Revard station Lowell's crevasse in long. 350° was 

 easily seen, cutting right through the cap. A large and 



probably indications of inequalities in the relief of the 

 polar areas. 



M. R. Jonckheere, observing with a 14-inch refractor 

 it the Hem Observatory^ (Roubaix), also directs attention 

 to this feature. On August 12 he observed (Astronomische 

 Nachrichten, No. 4354, p. 159) a " land " become detached 

 from the cap, although itself still covered with ice, and 

 identified it as Schiaparelli 's Xovissima 

 Thyle. On these grounds he suggests 

 (Compies rendus, No. 22, vol. cxlix., 

 p. 970) that the " lands " remain 

 covered with ice much longer than do 

 the "seas," thus producing apparently 

 irregular variations in the measured 

 diameters of the cap ; when, by the 

 planet's rotation, such an ice-covered 

 ■' land " is brought to the extremity of 

 the apparent ellipse, the major axis will 

 appear to be longer than when the 

 " land " is carried further round. M. 

 Jonckheere 's measures of the cap show 

 the following progression :— July 16, 

 32° (Martian arc) ; August 15, 18° ; 

 September 17, 9-3°; October 18, ii-S"; 

 November 18, 102°. On September 2, 

 Arg\re II. was seen, and its position 

 determined as long. 60°, lat. —80°; 

 this is nearer the pole than it has 

 hitherto been placed, and M. Jonck- 

 heere deduces, generally, that the lati- 

 tudes ascribed to the polar lands are 

 usually too small. .\nother mass was 

 seen, on the same evening, in long. 

 120°, lat. —84°, which apparently had 

 not been recorded before, and to this 

 M. Jonckheere gives the name " Stella," on account of its 

 brightness. " Thaumas " is the name given to another 

 new land which suddenly appeared in the Aonius Sinus, 

 touching Thaumasia, long. 100°, lat. —43°. 



-According to Prof. Lowell (Astronomische Nachrichten, 

 ^o- 437i> P- 47). the first snowfall of the season in the 

 Martian antarctic region took place on November 17 — 

 about two months after the summer solstice — when two 



jOe 



so « T* ao MS*«B1MH«^ 





V% , ^ — t t-^-i . JL . 1 1 i- — '•;. 



MtWtW.QOQOMeiSOIWtTO ■90 



Fig. 3. — Chart of Mars as observed by M. Antooiadi. 



brilliant spot near the edge of the cap, in long. 30°, was 

 also seen on July 4. The progressive diminution in size 

 and the changes in form, as observed by M. G. Fournier 

 at the Revard Observatory, are shown in Fig. 2, repro- 

 duced from a note by M. Desloges (Comptes rendus. 

 ^o. 26, vol. cxlix., p. 1347), who remarks on the increased 

 rate of diminution about August 15, and suggests that the 

 variations in detail and the time of disappearance are 



NO. 



2 1 19, VOL. 83] 



( patches in latitude —65" were seen in longitudes 100° 



I and 190°. 



M. Antoniadi also made observations, at the invitation 

 of M. Deslandres, with the 33-inch refractor of the Meudon 



I Observatory, the third largest refractor in general use. 

 He observed on thirty nights between September 20 and 

 November 9, but on about five nights onlv were the 



i atmospheric conditions really good. The results of his 



