July 1, 1897.] 



KNOWLEDGE. 



171 



but what is certain is that, in any case, it appeared large, 

 and was situated almost midway between the two Syrtes, 



Fig. G- — The Hourglass 

 Sea ovil864,November20tU. 

 (Franzenau.) 



Fig. 5. — The Hourglass Sea on 1864, November 22ik1. (Kaiser.) 



and very near the centre of the semicircular coast of 



Libya. 



In 1864 the "eagle-eyed" (though short-sighted") Dawes 

 continued the era so brilliantly 

 inaugurated by Lockyer in 1862, 

 furnishing us with a new set 

 of first-class drawings of the 

 planet. Dawes confirms his 

 predecessor's work, but shows 

 Libya as penetrating deeply into 

 the Hourglass Sea, whose breadth 

 is very much reduced in con- 

 sequence {see the Plate, Fig. 1); 

 its outer edge is a little shaded, 

 while Moeris Lacus, represented 

 as of very large size, is lying, as 

 in 1862, midway between the two 

 Syrtes. 

 We subjoin two other views taken during the same 



apparition of the planet, the 



first (Fig. 5) by Kaiser, 



showing the Nilosyrtis quite 



severed from the Major Syrtis 



— a phenomenon seen again 



by the Kev. T. E. R. 



Phillips, of Yeovil (Somerset), 



on January 15th of the 



present year ; the second 



(Fig. 6), by Von Franzenau, 



giving us an unusual visibility 



of the dusky " land " (Enotria, 



not unlike the appearance 



noted by the writer in Sep- 

 tember, 1896. 



Fig. 7 shows a remarkable 



and almost unique view of the Kaiser Sea, which is shown 



as quite separated from the Mare to the south by a bright 



bridge uniting Libya to Hammonis Comu. 



M. Terby, in 1873, gives a view of one of the bridges 



* It is scarcely likely that it is a matter of mere coincidence that 

 most of our greatest observers of planetary detail, such as Green, 

 Schiaparelli, and Stanley Williams, are all short-sighted men. 



Fio. 7. — The Hourglass Sea 

 on 1871, April 4th. (GledhUl.) 



Fig. 8.— The Hour- 

 glass Sea on 1873, 

 May 24th. (Terby.) 



discovered by the Parsonstown observers in 1862, and 

 stretching from Libya to Hellas (Fig. 8). 



In the same year, 1873, M. Flammarion made a sketch 

 (Plate, Fig. 2) of this region, which shows very neatly 

 that at that time the Hourglass Sea was quite as narrow 

 as it was ten years previously, and that the general con- 

 figuration of its eastern shores had undergone scarcely any 

 change since the oppositions of 1862 and 1861. 



During the famous opposition of 1877, the Syrtis Major 

 was smaller and narrower than perhaps it ever was since 

 its discovery by Huyghens. This shrinking was entirely 

 due to the invasion of ruddy material from Libya. In 

 October, 1877, the Syrtis appeared to end almost at the 

 latitude of Moeris Lacus. The accompanying sketch by 

 Schiaparelli (Fig. 9) will make these descriptions plain. 

 Libya penetrated deeply into the greyish 

 area of the Sea, forming a graceful 

 curve extending right down to the 

 sharply pointed Osiridis Promontorium, 

 in 28° of north latitude. The 

 accuracy of these observations is fully 

 confirmed by Mr. Green's drawings, 

 taken at Madeira in 1877, and consti- 

 tuting, as Mr. Maunder says, the most 

 lifelike representations of the planet 

 ever published. 



In 1879 the Hourglass Sea appeared 

 much broader from the disappearance of Osiridis Pro- 

 montorium. An immediate consequence of this invasion 

 of the dark material was that Lake Moeris seemed no 

 longer situated midway between the Syrtes, but at rather 

 less than one-third the distance separating the embouchure 

 of the Nepenthes from the Lesser Syrtis. A characteristic 

 feature of the 1879 apparition was a slight shading of the 

 south-western segment of Libya (Plate, Fig. 3). 

 Analogous phenomena were noted in 1881-1882. 



The next op- 

 position of 1883- 

 1884 was marked 

 by a further step 

 in the invasion of 

 the dark material 

 of the Syrtis over 

 dusky Libya. At 

 this time no more 

 than a hundred 

 miles separated 

 the lake from the 

 sea, while the 

 brightness of 

 Libya had under- 

 gone a further 

 diminution. 



In 1886 and 

 1888 the progress 

 of the dark in- 



Fig. 



9.— The Hourglass Sea on 1877, 

 October 14th. (Schiaparelli.) 



vasion was a very 

 languid one. A sketch by Schiaparelli (Fig. 4 of the 

 Plate) shows Libya always shaded, while the gemination 

 of the Nepenthes Canal and the shrinkage of Mceris Lacus 

 are highly interesting. 



The general configuration of this part of the planet 

 underwent no striking changes in 1890. Nepenthes was 

 always double ; but the darkness of Libya was occasionally 

 very intense, and, at times, so marked as to "flood" to 

 disappearance Lake Mceris in this sombre background 

 (Fig. 5 of the Plate). 



A drawing taken in 1892 by Mr. Walter Gale at Sydney, 

 New South Wales, shows some remarkable changes in the 



