November 5, 1909] 



SCIENCE 



645 



Eighth Step. — Concurrently with these con- 

 structive attempts of Chamberlin with futile 

 results except as based on planetoidal lines, 

 Moulton attempted a critical review of all 

 recorded cosmogonic hypotheses, but unfore- 

 seen conditions caused the temporary suspen- 

 sion of work and prevented a final treatment 

 and publication of the assembled material." 



Ninth Step. — With (1) an open door for 

 constructive work with nebulfe of planetoidal 

 dynamics made available in 1897, with (2) the 

 controlling criteria defined, and with (3) the 

 limitations of tenable hypotheses narrowed by 

 the futile work, the planetesimal hypothesis 

 was gradually given shape and working form 

 chiefly by Chamberlin in the absence of Moul- 

 ton, as set forth in Year Book No. 3, Carnegie 

 Institution, 1904, pp. 208-233 ; but this shaping 

 of the hyiDothesis passed under the criticism 

 of Moulton before publication. The spirit 

 and purpose of this constructive work is thus 

 stated, pp. 232-233: 



It has thus been my endeavor to develop the 

 hypothesis into sufficient detail { 1 ) to furnish a 

 large number of points of contact with known 

 phenomena and with recognized mechanical prin- 

 ciples to facilitate testing its verity by those 

 relations, if not now, at least in the early progress 

 of investigation; (2) to furnish a basis for de- 

 ducing the hypothetical stages of the earth that 

 preceded its known history, and for drawing 

 thence inferences as to the conditions of the in- 

 terior which the earth inherited from the mode 

 of its birth; and (3) to stimulate inquiry into the 

 elements involved. In short, I have endeavored 

 to give tlie hypothesis a working form under the 

 conviction that so long as the complicated ele- 

 ments involved remain so imperfectly determined 

 as at present its working value is its chief value. 



Preliminary to this publication the essen- 

 tial features of the hypothesis had been dis- 

 cussed before several scientific societies and 

 subjected to criticism. The hypothesis was 

 also set forth by Moulton in a paper " On the 

 Evolution of the Solar System," Astrophys. 

 Jour., October, 1905, pp. 165-181. 



Later Steps. — The hypothesis was somewhat 

 further elaborated and supplied with illustra- 



° Moulton in Year Book No. 3, Carnegie Insti- 

 tution, 1904, pp. 2.55-256. 



tions for text-book use by Chamberlin for the 

 chapter on the Origin of the Earth in Cham- 

 berlin and Salisbury's " Geology," Vol. II., 

 Chap. I., pp. 28-81, 1905, and by Moulton for 

 his " Introduction to Astronomy," 1906, pp. 

 463-487. 



Subsequent work in further testing, devel- 

 oping and applying the hypothesis has been in 

 progress as set forth in Year Book No. 4, 

 Carnegie Institution, 1905, pp. 171-173 

 (Chamberlin), and 186-190 (Moulton); Year 

 Book No. 5, Carnegie Institution, 1906, pp. 

 165-172, and in later Year Books. More 

 specifically and concretely, the continuation of 

 investigation on lines growing out of the 

 planetesimal hypothesis is shown by Publica- 

 tion No. 107, of the Carnegie Institution, en- 

 titled "The Tidal and Other Problems." 



T. C. Chamberlin 



F. E. MOULTON 



Chicago, 



October 14, 1909 



AN ASSOCIATION OF AMERICAN CHEMICAL 

 RESEARCH LABORATORIES 



To THE Editor of Science: In connection 

 with the second decennial celebration of Clark 

 University, a special meeting was held on 

 September 16 last " for the purpose of forming 

 an Association of Chemical Research Labora- 

 tories, to systematically exchange chemicals 

 urgently needed in research work." Many of 

 your readers will doubtless be interested to 

 know the outcome of that meeting. 



Chemical research, especially organic re- 

 search, in this country is greatly handicapped 

 by the length of time it takes to import chem- 

 icals from Germany, when a need for them 

 arises unexpectedly in course of an investiga- 

 tion. To quote a single opinion expressed at 

 our September meeting, Professor Arthur 

 Michael declared that his output of work, 

 during the past twenty-five or thirty years, 

 has been reduced fifty per cent, by this handi- 

 cap. 



Now, a chemical urgently needed in one 

 laboratory is very often lying unused in some 

 other laboratory. It would be gladly placed 

 at the disposal of the investigator who hap- 



