874 



SCIUNGE 



[N. S. Vol. XXXIV. No. 8«« 



Ames, "Theory of Physics'" (1S97), page 398: 

 '■'. . . when the satellite will disappear behind 

 Jupiter, i. e., be eclipsed." 



Watson, "A Text-book of Physics" (1899), 

 page 505: "... when Jupiter and the earth are 

 nearest together (at conjunction), and that which 

 occurs -when they are at their greatest distance 

 (opposition)." 



Eowlaud and Ames, "Elements of Physics" 

 (1900), page 172: "... and so, if the eclipses of 

 a satellite behind a planet's disc. ..." 



Eggar, "Wave-motion, Sound, Light" (1901), 

 .page 504: "... the times of eclipse of one of 

 the moons, i. e., the instants at which it should 

 pass behind the planet and emerge from his 

 shadow. ' ' 



Crew, "Elements of Physics" (1906), page 

 311: "Jupiter has five moons, one of which is 

 larger and brighter than any of the others, and is 

 called the 'first satellite.' " See also "General 

 Physics" (1908), page 429. 



Henderson and WoodhuU, "Elements of Phys- 

 ics" (1906), -page 290: "The eclipse was seen 

 while the earth and Jupiter were on the same side 

 of the sun — as the astronomers say, 'in conjunc- 

 tion' — the time was 16' 36" earlier than when the 

 earth and Jupiter were on opposite sides of the 

 sun ; that is ' in opposition. ' ' ' 



Millikan and Gale, "A First Course in Phys- 

 ics" (1906), page 388: "Eoemer was making ob- 

 servations on the largest and brightest of Jupiter 'g 

 seven moons. " " Eoemer first determined the in- 

 terval between two successive eclipses, . . . and 

 foimd it to be 48 hr. 28 min. and 36 sec. ' ' 



Gage, as revised by Goodspeed, "Principles of 

 Physics" (1907), page 276: "He made observa- 

 tions on that one of the five of Jupiter's satellites 

 which is nearest to the planet. ' ' 



Duff (editor), "A Text -book of Physics" 

 (1908), page 339: ". . . when Jupiter and the 

 earth are in conjunction, or on the same side of 

 the sun and in line with it. " "... at opposi- 

 tion, when the earth is on the opposite side of the 

 sun from Jupiter. ' ' 



Leaving out of consideration the number of 

 Jupiter's satellites at any date, each of the 

 above quotations has one error and some of 

 them two. In many books it is stated that 

 Eoemer found the time for the light to cross 

 the earth's orbit to be 16 min. 36 see. This is 

 nearly the present accepted value, while that 



deduced by Roemer was considerably greatei, 

 some 22 min. 



C. A. Chant 

 Univeesity or Toronto 



AIR IN THE DEPTHS OF THE OCEAN 



To THE Editor of Science: With reference 

 to the communications appearing in the issues 

 of August 25 and October 27 in relation to 

 " air in the depths of the ocean," while it is 

 erroneous to hold that the amount of dissolved 

 gas is dependent upon hydrostatic pressure, 

 yet the gas content of the bottom waters may 

 be greater than the gas content of the surface 

 waters because of the greater solubility of the 

 gases -at the low temperatures prevailing in 

 the depths of the ocean. Sea water contains, 

 in proportions varying widely with circum- 

 stances, four gases — oxygen, nitrogen, carbonie 

 acid and argon. The oxygen decreases and 

 the carbonic acid increases with increasing 

 depth; but there is a respiratory process in 

 operation by which the carbonic acid ascends 

 by diffusion right up to the surface, while the 

 oxygen by the same means makes its way to 

 the bottom. This allows us to understand how 

 the supply of oxygen, which is indispensable 

 to the life of the animals everywhere existing 

 in the depths of the ocean, is renewed even 

 down to the bottom and an exchange made 

 between the carbonic acid gas produced by 

 their respiration and the oxygen coming from 

 above. G. W. Littlehales 



contagious abortion of cattle 

 To THE Editor of Science: In a recent 

 number (October 13) Director H. L. EusseU, 

 of the Wisconsin Agricultural Experiment 

 Station, announces the discovery of the fact 

 that the contagious abortion of cattle in this 

 country is identical with that of Europe, and 

 due to the B. ahoj-ti^s of Bang. Professor 

 Russell apparently regards the investigations 

 carried out at the Wisconsin Station since 

 May, 1911, as the first creditable bacteriolog- 

 ical work upon this subject in this country, 

 and his commmiieation would seem to cast 

 some doubt upon the accuracy of the observa- 



