ft' 



otography 

 ots 



SCIENTIFIC SIDE-LIGHTS 



526 



the action of the photograph, on the con- 

 trary, the effect does accumulate, and in the 

 case of a weak light accumulates indefi- 

 nitely. It is owing to this precious property 

 that, supposing (for illustration merely) 

 the lightning flash to have occupied the one- 

 thousandth part of a second in impressing 

 itself on the plate, to get a nearly similar 

 effect from a continuous light one thousand 

 times weaker, we have only to expose the 

 plate a thousand times as long that is, for 

 one second; while from a light a million 

 times weaker we should get the same result 

 by exposing it a million times as long that 

 is, for a thousand seconds. LANGLEY New 

 Astronomy, ch. 8, p. 244. (H. M. & Co., 1896.) 



2593. PHOTOGRAPHY FINDS NO 

 TRACE OF SUNLIGHT IN DEEP SEA 



The more recent experiments that have been 

 made tend to show that no sunlight what- 

 ever penetrates to a greater depth, to take 

 an extreme limit, than 500 fathoms. Fol 

 and Sarasin, experimenting with very sensi- 

 tive bromo-gelatin plates, found that there 

 was no reaction after ten minutes' exposure 

 at a depth of 400 meters on a sunny day 

 in March. HICKSON Fauna of the Deep Sea, 

 ch. 2, p. 25. (A., 1894.) 



2594. PHOTOGRAPHY PICTURES THE 

 INVISIBLE Finds Stars in the Blackness of 

 Space. Mr. H. C. Russell, at Sydney, in 

 1890, successfully imitated Professor Bar- 

 nard's example. His photographs of the 

 southern Milky Way have many points of 

 interest. They show the great rift, so black 

 to the eye, as densely star-strewn to the 

 perception of the chemical retina, while 

 the " Coal-sack " appears absolutely dark 

 only in its northern portion. CLERKE His- 

 tory of Astronomy, pt. ii, ch. 12, p. 508. 

 (BL, 1893.) 



2595. The Photograph 



Secures What the Telescope Fails to Reveal 

 One Hour of Photographic Exposure Sur- 

 passes Years of an Astronomer's Labor. 

 The writer remembers the interest with 

 which he heard Dr. Draper, not long before 

 his lamented death, speak of the almost 

 incredible sensitiveness of these most re- 

 cent photographic processes, and his belief 

 that we were fast approaching the time 

 when we should photograph what we could 

 not even see. The time has now arrived. 

 At Cambridge, in Massachusetts, and at 

 the Paris Observatory, by taking advantage 

 of the cumulative action we have referred 

 to, and by long exposures, photographs have 

 recently been taken showing stars absolutely 

 invisible to the telescope, and enabling us 

 to discover faint nebulae whose previous ex- 

 istence had not been suspected; and when 

 we consider that an hour's exposure of a 

 plate now not only secures a fuller star- 

 chart than years of an astronomer's labor, 

 but a more exact one, that the art is every 

 month advancing perceptibly over the last, 

 .and that it is already, as we may say, not 



only making pictures of what we see, but of 

 what we cannot see even with the telescope, 

 we have before us a prospect whose possi- 

 bilities no further words are needed to sug- 

 gest. LANGLEY New Astronomy, ch. 8, p. 

 247. (H. M. & Co., 1896.) 



2596. PHRENOLOGY, ABSOLUTE LIM- 

 IT OF Power of Brain Dependent on Convo- 

 lutions. No account can be taken [by 

 phrenology] of an increased number of con- 

 volutions. Supposing that the size of each 

 faculty be due to the amount of gray mat- 

 ter in the convolution, then an additional 

 convolution will greatly increase the amount 

 of gray matter, but will not alter the shape 

 of the skull situated above this portion of 

 the brain. This is important, as, from ob- 

 servations which have been made, it is found 

 that the brain is more convoluted in persons 

 of superior intelligence. ELDBIDGE - GREEN 

 Memory and Its Cultivation, ch. 5, p. 38. 

 (A., 1900.) 



2597. PHRENOLOGY IGNORES ELE- 

 MENTS Answers Problem by Restatement. 

 Phrenology hardly does more than restate 

 the problem. To answer the question, " Why 

 do I like children?" by saying, "Because you 

 have a large organ of philoprogenitiveness," 

 but renames the phenomenon to be ex- 

 plained. What is my philoprogenitiveness? 

 Of what mental elements does it consist? 

 And how can a part of the brain be its 

 organ? A science of the mind must reduce 

 such complex manifestations as " philopro- 

 genitiveness " to their elements. A science 

 of the brain must point out the functions 

 of its elements. A science of the relations 

 of mind and brain must show how the ele- 

 mentary ingredients of the former corre- 

 spond to the elementary functions of the 

 latter. But phrenology, except by occasion- 

 al coincidence, takes no account of elements 

 at all. JAMES Psychology, vol. i, ch. 2, p. 

 28. (H. H. & Co., 1899.) 



2598. PHYSICS, CELESTIAL The New 



Contrasted with the Old Astronomy Study 

 of the Nature, and Not Merely of the Po- 

 sition, of the Heavenly Bodies. The prime 

 object of astronomy, until very lately, in- 

 deed, has still been to say where any heaven- 

 ly body is, and not what it is. It is this 

 precision of measurement, then, which has 

 always and justly been a paramount ob- 

 ject of this oldest of the sciences, not only 

 as a good in itself, but as leading to great 

 ends; and it is this which the poet of Urania 

 has chosen rightly to note as its character- 

 istic when he says: 



That little vernier, on whose alender lines 



The midnight taper trembles as it shines, 



Tells through the mist where dazzled Mercury burns, 



And marks the point where Uranus returns. 



But within a comparatively few years a 

 new branch of astronomy has arisen which 

 studies sun, moon, and stars "for what they 

 are in themselves and in relation to our- 

 selves. Its study of the sun, beginning with 

 its external features (and full of novelty 



