July 4, 1884.] 



SCIENCE. 



29 



importance. The application of mathematics to ter- 

 restrial physics has too often been fruitless from 

 dealing with problems in a simplified or idealized 

 form that departs too widely from the complications 

 of natural conditions. This was notably the case 

 with the supposed demonstrations obtained by Hop- 

 kins in his geological speculations. It is therefore 

 gratifying to find that the increased value of von 

 Baer's law, now found by Gilbert, comes essentially 

 from a close consideration of the actual rather than 

 of the ideal conditions of river-flow. It is an ad- 

 vance in the application of mathematics as well as 

 in the explanation of facts. 



The lateral tendency of rivers was first noticed in 

 the case of the Yolga, which undercuts its right 

 bank, as it should in this hemisphere. Other exam- 

 ples are found in North Carolina, in the channels of 

 the streams flowing eastward to the coast, where the 

 southern banks are the steeper ; again on Long Is- 

 land, and on the plains of New Zealand. But the 

 radial valleys of south-western France afford better 

 illustrations than any of these, inasmuch as their 

 forms are accurately shown on the great map of the 

 army engineers. North of the Pyrenees, about the 

 towns of Tarbes and Auch, there is an old sandy 

 delta deposit spread out by the rivers from the moun- 

 tains while this region was still under water ; and 

 since its elevation, the streams formed upon it all 

 follow its gentle slopes, diverging like the ribs of a 

 fan from the higher centre toward the lower margin, 

 and cutting down their channels into the old delta 

 plain. There is nothing here in the flat layers of 

 unconsolidated sands to determine an unsymmetri- 

 cal form in the valleys : and yet they all show most 

 distinctly a gentle slope on the left, and a steeper slope 

 on the right ; longer lateral branches on the left, and 

 shorter ones on the right ; and many of the highways, 

 constructed parallel to the streams on the as yet un- 

 broken uplands, are clearly closer to the streams on 

 their left than on their right. All this is a direct 

 effect of the earth's rotation. 



It is customary, in speaking of the deflective force 

 that arises from the earth's rotation, to say that it 

 acts to the right in the northern hemisphere, but to 

 the left in the southern. The reason for this is not 

 found in a change in the direction of the force, but 

 only in a change in our way of looking at it. It is 

 as if one should look at the face of a watch in the 

 northern hemisphere, and say that the hands turn to 

 the right, and then, on going to the southern hemi- 

 sphere, look at the back of the watch, and say that the 

 hands turn to the left. Let us therefore suggest that 

 the geographers of the southern hemisphere look at 

 their winds and storms and streams from the proper 

 side, just as they look at their watches ; and, although 

 this would involve them in the slight inconvenience 

 of standing on their heads, it would give them the 

 moral satisfaction of seeing that the deflective forces 

 of the earth's rotation, as well as the hands of their 

 watches, always ' make for the right.' 



— Mr. Lockyer has given an account of a recent 

 visit to the observatory at Nice, the building of which 

 is due to the munificence of Mr. Bischoffsheim, the 



well-known French banker. In connection with this, 

 Mr. Lockyer presents some striking ideas respecting 

 the future of physical observations of the heavenly 

 bodies. He suggests that it is now time to abolish the 

 observer entirely, and that any astronomer would be 

 losing his time by attempting to draw either the 

 nebula of Orion or the spectra of stars. Photography 

 should take the place of hand-drawing for both of these 

 purposes. He pictures an astronomer, one thousand 

 years hence, in a room filled with photographs giv- 

 ing a picture of every part of the heavens, from pole 

 to pole, as it appears to us in the nineteenth century. 

 By using a different form of telescope, the expense of 

 a dome could be avoided. Altogether, Mr. Lockyer' s 

 suggestions are well worthy the attention of all en- 

 gaged in planning observatories. 



— In 1885 an exhibition of inventions is to be held 

 at South Kensington under the patronage of the 

 Prince of Wales. The first part of the exhibition is 

 to be of all inventions made or brought into use since 

 1882; the second part is to be of all musical instru- 

 ments invented since 1800. The committee of the 

 first exhibition includes many of the most eminent 

 scientific men in England. 



— The Illustrirte zeitung reports an interesting dis- 

 covery in the department of photography. Eleven 

 years ago Professor Vogel of Berlin explained a method 

 by which the effects of colors, such as blue and yellow, 

 might remain unchanged as to light and shade, and 

 which would overcome this difficulty of photography. 

 He has now worked out a process on this principle 

 with practical success : it is published in the Photo- 

 graphischen mittheilungen, and the German photo- 

 graphic society has awarded him a prize for it. 



— Professor Carnoy, of the Catholic university of 

 Bouvain, announces a work on ' Biologie cellulaire,' 

 which will treat of the general characters of cells, both 

 animal and vegetable. He proposes to deal with the 

 general organization, chemistry, and physiology of 

 cells, basing his work upon original observations, 

 either new, or confirmatory of previous researches. 

 He promises over four hundred new illustrations, en- 

 graved with great care and accuracy. The scheme 

 is ambitious; but, if well carried out, it will secure us 

 a valuable book on an aspect of biology too little 

 heeded at present. Professor Carnoy is a botanist, 

 whose reputation will rise high if his volume fulfils 

 the promises of the prospectus. It is to be published 

 at Lierre, Belgium, by Joseph Van In & Cie. The 

 price to subscribers is twenty-five francs. 



— If an observatory is to be judged by the number 

 of its astronomers and the variety of its work, that 

 of Paris must rank as the first in the world. The 

 most important work now in progress is the construc- 

 tion of the great catalogue of stars observed during 

 the past thirty years, the printing of which has been 

 commenced. The Bischoffsheim circle, known as 

 the ' cercle du jardin,' has thus far been used only 

 for day observations. One of the most important 

 improvements has been the introduction of the shal- 

 low amalgamated basin for holding the quicksilver 

 used in the artificial horizon. Very careful experi- 



