Chemistry and Physics, 543 



Jupiter, when in a fluid state, to throw off pairs of planets ; the 

 smaller twin being born from the region of greatest curvature 

 nearest to the sun, and the larger twin being dropped from the 

 most remote region of least curvature. 



"Jupiter's aphelion distance was decreasing and his peri- 

 helion distance was increasing, while his entire orbit was becom- 

 ing more and more circular. The first interior planet was 

 dropped at a time when Jupiter's perihelion was very near the 

 sun and when his orbit reached the limit of its elongation, and 

 he dropped the outermost planet at the same time, but from his 

 opposite side. So the first small planet and the first, or outer- 

 most, big planet are of the same age." "Saturn and the 

 asteroids are the youngest set of planetary children; Mars and 

 Uranus are the next youngest in our system; then come Earth 

 and Neptune. This arrangement leaves Venus and Mercury 

 unpaired. " "So not only do I assert that the two undiscovered 

 planets are there, but I assert without the suggestion of a doubt 

 that they must be there. ' ' 



The author 's style is generally clear and attractive, and he ' 

 presents his case in a very plausible manner. Nevertheless, 

 since the deductions are not based on mathematical calculations 

 it remains to be seen whether the "theory" will stand the test 

 of rigorous, quantitative analysis. H. s. u. 



6. Ozone, and the Ultra-violet Transparency of the Lower 

 Atmosphere. — The absorption of ultra-violet light by the atmos- 

 phere near the surface of the earth has been recently studied 

 experimentally by R. J. Strutt. For distances up to 1200 

 yards a spark between cadmium electrodes was used as source. 

 For the greatest distance available, namely 4 miles, a quartz 

 mercury vapor lamp was employed. The spectrograms were 

 taken with a small prismatic camera containing a single 60° 

 quartz prism and a quartz lens of 1 inch aperture and 5 inches 

 focal length. The source of light was placed behind a quartz 

 lens of 3-5 inches diameter in order to focus the radiations on 

 the distant station. Under these circumstances, the monochro- 

 matic images were round dots instead of the usual spectral lines. 

 Lack of an assistant necessitated adjusting the apparatus in the 

 daytime and taking the exposures at night. 



"The spectrum of the cadmium spark taken at 3600 feet 

 showed no definite indication of ozone, the whole spectrum being 

 transmitted .to A 2313, right through the region, near A 2536, 

 where ozone absorption is a maximum." An exposure of two 

 hours, taken on a clear night with the mercury lamp at a distance 

 of four miles, recorded the spectrum as far as A 2536. This 

 result may be compared with the limit, A 2922, of the solar 

 spectrum, as obtained by Simony on the Peak of Teneriffe. 

 When reduced to standard conditions, the thickness of air 

 traversed by the solar light was not greater than 17,900 feet 

 whereas the layer of air was not less than 20,100 feet in the 



