METHODS OF THE EARTH-SCIENCES 483 



certain extremes on either hand. If a series of values ranging from 

 the one extreme to the other be used simultaneously in the inquiry, the 

 full range of results dependent on this factor may be covered. In some 

 inquiries this serves as well as if the exact truth were known, for what- 

 ever the assignable value, certain deductions cannot stand. In other 

 cases it will be shown that a very slight change in the value of the 

 basal factor will wholly change the outcome, and hence that ex- 

 tremely accurate determinations must be made before any trust- 

 worthy solution can be reached. Expensive determinations in the 

 first case are folly; very accurate determinations in the second are to 

 be sought at any cost. Conclusions on imperfect data in the one case 

 are perfectly safe; conclusions without precise determinations in the 

 other are folly. It is to be hoped that, with the wider adoption of the 

 method of multiple series, tables of serial determinations covering 

 the data of the more vital phenomena of the earth-sciences will be 

 constructed, as tables of physical constants now are. 



The Method of Regenerative Hypotheses 



In the method of multiple hypotheses, the members of the group 

 are used simultaneously and are more or less mutually exclusive, or 

 even antagonistic. Supplementary to this method is the use of a 

 succession of hypotheses related genetically to one another. In this 

 the results of an inquiry under the first hypothesis give rise to the 

 assumptions of the succeeding hypothesis. The precise conclusions 

 of the first inquiry are not made the assumptions of the second, for 

 the process would then be little more than repetitive, but the re- 

 velations and intimations, perhaps the incongruities and incompat- 

 ibilities, of the first results beget, by their suggestiveness, the basis 

 of the second. The latter is the offspring of the former, but between 

 parent and offspring there is mutation with an evolutionary purpose. 

 A cruder first attempt generates a more highly organized and spe- 

 cialized working scheme fitted to the new state of knowledge de- 

 veloped. The method is specially applicable to elaborate inquiries, 

 particularly those in which the premises are imperfect and a long 

 logical chain is hung upon them. The discussions of our great funda- 

 mental conceptions furnish the best examples, chiefly examples of 

 the lack of a systematic regenerative method. Among these, two 

 general classes may be recognized, (1) those of a rather rigorous 

 type, as, for a distinguished example, the researches of George Dar- 

 win on tidal reaction and the history of the earth and moon, and 

 (2) those of a looser and sometimes rather metaphysical type, which 

 I shall try to illustrate by the doctrine of determinism. In all cases, 

 assumptions are made the basis of the procedure. Absolute premises 

 are not available. Taking its start from these assumptions, the 



