PLATEAU ON SOAP-BUBBLES. 399 



times they appear tedious on account of repetitions, we must remember that it 

 is by words, and words alone, that the author can learn the details of the 

 experiment which he is performing by means of the hands of his friends, and 

 that the repetition of phrases must in his case take the place of the ordinary 

 routine of a careful experimenter. The description of the results of mathematical 

 investigation, which is a most difficult but at the same time most useful species 

 of literary composition, is a notable feature of this book, and could hardly be 

 better done. The mathematical researches of Lindelof, Lamarle, Scherk, Blemann, 

 &c., on surfaces of minimum area, deserve to be known to others besides pro- 

 fessed mathematicians, and M. Plateau deserves our thanks for giving us an 

 intelligible account of them, and still more for shewing us how to make them 

 visible with his improved soap-suds. 



In the speculative part of the book, where the author treats of the causes 

 of the phenomena, there is of course more room for improvement, as there 

 always must be when a physicist is pushing his way into the unknown regions 

 of molecular science. In such matters everything human, at least in our century, 

 must be very imperfect, but for the same reason any real progress, however 

 small, is of the greater value. 



