384 Chronicles of Science. [July, 



mination of the epoch (850,000 years ago) at which the earth's 

 orbit attained the greatest eccentricity it has had during the past 

 million years is due to the labours of Mr. Croll, who has calculated 

 a table exhibiting the eccentricity, position of perihelion, &c, of the 

 earth's orbit during the above-named interval. 



We remind our readers that on the 21st of August, Jupiter will 

 be without visible satellites from lOh. 4m. p.m. to llh. 49m. p.m. 

 The hours of disappearance and re-appearance of the several 

 satellites were given in our last. 



On August 9th, 10th,^ and 11th, the St. Lawrence meteor- 

 shower may be looked for. Unlike the November star-shower, the 

 August shooting-stars appear almost as frequently before as after 

 midnight, the radiant-point being above the horizon throughout the 

 night. 



On April 3rd, M. Tempel detected a telescopic comet. 



Proceedings of the Astronomical Society. 



Mr. Tennant has computed the path of the moon's shadow, 

 August, 1868, across the peninsula of India. The central line 

 passes from near Tiziadroog, on the western coast, to near Masuli- 

 patam on the eastern, the duration of total obscuration being 

 5m. 12s. at the first place, and 5m. 45s. at the second. 



]\Ir. Brothers succeeded in taking twenty photographs of the 

 sun during the eclipse of March 6th. Mr. Browning's observation 

 of the eclipse is noteworthy on account of the application of a novel 

 method of viewing the sun. A disc of glass having plane and 

 parallel sides was inserted in the open end of a reflecting telescope. 

 The outer side of the disc was coated with a thin film of pure 

 silver, by Liebig's process. This delicate metallic film reflected 

 nearly the whole of the heat, and the greater portion of the light 

 of the sun's rays, its transparency being sufficient, however, to 

 enable enough light to pass through it into the telescope to render 

 very small markings on the sun's surface plainly discernible. 



Mr. Stone discusses the possibility of a change in the position of 

 the earth's axis, owing to "frictional action connected with the 

 phenomena of the tides." After a careful examination of two 

 hypotheses, between which the truth in all probability lies, he 

 arrives at the conclusion that the friction al action of the tides " is 

 not available as an explanation of those secular changes of climate 

 which geologists have shown to have taken place on our earth." 



Mr. Joynson presents the results of observations of the planet 

 Mars during the late opposition. He considers that there is a 

 permanent dark band extending all round the planet, with only one 

 narrow break in it. But this description is tar from presenting the 



