Editoeial Committee : S. Newcomb, Mathematics ; R. S. Woodwaed, Mechanics ; E. C. Pickeeinr, 



Astronomy ; T. C. Mendenhall, Physics ; R. H. Thurston, Engineering ; Iea Rejisen, Chemistry ; 



Joseph Le Conte, Geology ; W. M. Davis, Physiography ; Henry F. Osboen, Paleontology ; 



W. K. Beooks, C. Haet Meeeiam, Zoology ; S. H. Scudder, Entomology ; C. E. Bessey, 



N. L. Britton, Botany ; C. S. Minot, Emhryology, Histology ; H. P. BoWDiTcn, 



Physiology ; J. S. Billings, Hygiene ; William H. Welch, Pathology ; 



J. McKeen Cattell, Psychology ; J. W. Powell, Anthropology. 



Friday, Octobek 26, 1900. 



CONTENTS: 



The Intirferences observed on riewing one Coarse 

 Grating through another and on the Projection of 

 one Piece of Wire Gauze hy a Parallel Piece: 

 Peofessor Carl Baeus 617 



The Crossley Reflector of the Lick Observatory : Peo- 

 PESSOE C. D. Perrine 627 



The Address of the President of the Chemical Section 

 of the British Association for the Advancement of 

 Science: Professor W. H. Perkin 632 



Scientific Books : — 



Suess's La face de la terre : J. B. WoODWOETH ; 

 Vigneron and Letheule's Mesures elecirique, 

 de Villemontee' s Resistance Slectrique et fluidite : 

 Professor W. S. Feanklin. Books Received. 645 



Scientific Journals and Articles 648 



Societies and Academies : 



The Philosophical Society of Washington : J. H. 

 H A YFORD .• The A eademy of Science of St. Louis : 

 Professor William Teelease 648 



Discussion and Correspondence : — 



Arithmetical Note : PeofesSOE C. A. ScOTT ; 

 Camphor secreted by an Animal: NATHAN 

 Banks ; A Correction : Peofessoe J. W. Fee- 

 ley 648 



Botanical Notes : — 

 Prolixity in Botanical Papers; The Study of 

 Plant Diseases ; The Annual Shedding of Cotton- 

 wood Tioigs ; The Immediate Effect of Pollen : 

 Peofessoe Chaeles E. Bessey 649 



The New York Botanical Garden 651 



Scientific Notes and News 652 



University and Educational News 656 



MSS. inteDded for publication and books, etc., intended 

 for review should be sent to tbe responsible editor, Profes- 

 sor J. McKeen Cattell, Garrison-on-Hudson, N. Y. 



TffE INTERFERENCES OBSERVED ON VIEW- 

 ING ONE COARSE GRATING THROUGH AN- 

 OTHER, AND ON THE PROJECTION OF 

 ONE PIECE OF WIRE GAUZE BY 

 A PARALLEL PIECE. 

 It has often been a matter of surprise to 

 me that the shadow bands observed, for 

 instance, on looking through one distant 

 picket fence at another, are so seldom re- 

 ferred to in the literature of physics ; and 

 moreover, that phenomena so ubiquitous 

 and of such remarkable properties are spar- 

 ingly, if ever, made use of by the practical 

 physicist. I therefore thought it worth 

 while to look into the subject experiment- 

 ally, for my own satisfaction, and the re- 

 sults may be of interest to the reader. I 

 hope to show that there is probably no more 

 straightforward example of the dififraction 

 method in geometric optics, or more instruc- 

 tive method of introducing it. 



CERTAIN ALLIED SIMPLE PHENOMENA. 



1. If a piece of wire gauze is placed on 

 another with the wires nearly parallel, the 

 well-known water lines invariably come out, 

 oftentimes, if one piece of gauze is regu- 

 larly or geometrically crumpled or dimpled, 

 showing beautiful patterns. The explana- 

 tion of this is at hand ; the upper meshes 

 being nearer the eye subtend a larger angle, 

 and when both are projected on the same 

 plane, two scales result, one a little larger 

 than the other. Hence, similar to the case 

 of the vernier or the analogous case of 



