Intelligence and Miscellaneous Articles, 397 



The Structure of tlie Sidereal Universe. By T. W. Backhouse, 

 F.B.A.S. Demy 4to. Hills & Co., Sunderland. 

 No. 1 of the ' Publications of the West Hendon House Observa- 

 tory, Sunderland/ by T. W. Backhouse, has just been issued, and 

 gives the details on which the author's previous papers " On the 

 Structure of the Sidereal Universe " (published in the ' Monthly 

 Notices,' vol. i. p. 374, and in the ' Sidereal Messenger,' vol. ix. 

 p. 337) were founded. The work is illustrated with figures and 

 maps, and the numerous observations summarized in the text 

 furnish a useful contribution to one of the grandest problems in 

 astronomy. Mr. Backhouse's instruments are a 2-inch field-glass 

 and a 4|-inch refracting telescope, and he appears to have made ex- 

 cellent use of them. He remarks that certain large diffused nebu- 

 losities seen by Sir "W. Herschel do not agree with those seen in a 

 field-glass. This is not surprising when we reflect that Herschel 

 used powerful appliances in his unwearying examination of the 

 hevaens. Mr. Backhouse says : — "We are brought to the conclusion 

 that the galaxy is probably far nearer us than was at one time 

 believed, and that therefore the greater part of the stars composing 

 it are likely to be much smaller than the sun. The tendency of 

 modern investigations is to diminish our ideas of the extent of the 

 visible universe." 



Astronomers will welcome further publications from the obser- 

 vatory at Sunderland. Private efforts of this laudable character 

 are none too numerous in this country. 



LI. Intelligence and Miscellaneous Articles. 



RETINAL OSCILLATIONS. BY M. CHARPENTIER. 

 T HA YE recently investigated certain phenomena which, viewed 

 as a whole, demonstrate experimentally the production of oscilla- 

 tions in the visual apparatus, when excited by light. These oscil- 

 lations seem rather connected with a reaction of the retina, when 

 it is acted on by light, than with the act of sensation itself. They 

 are none the less interesting to know, and may serve as starting- 

 point for a more minute analysis of the mechanism of the act in 

 question. 



The fact which led to these researches, and which I had com- 

 municated to the Societe de Biologie on May 10, 1890, is the 

 following : — If a black disk, on which is a larger or smaller white 

 sector, is turned rather slowly, and if the centre of the disk is 

 rigidly viewed when it is brightly illuminated, it is observed that 

 that side of the white sector which first penetrates over the dark 

 ground is bordered in its motion by a very sharp black band sepa- 

 rated from the ground by a similar white band. These two bands 

 appear in the form of sectors concentric with the disk, provided 

 that certain necessary precautions are taken in the observation, in 

 the detail of which I cannot enter here. The black band is shaded 

 off at the edges ; its angular extent, like that of the original white 

 band, increases with the velocity of the disk, and in proportion to 



