Eleventh Year. 

 Vol. XXI. No. o24. 



FEBRUARY" 1?, 1893. 



Single Copies, Ten Cents. 

 $3.50 Per Year, in Advancb. 



Contents. 



A Remarkable Occurrence of Selenite. J. E. 

 Talmage 



The Future Ohm, Ampere, and Volt. Henry 

 S. Carhart ■ 



The Classification and Naming op Igneous 

 Bocks. W. S. Bailey 



Cloud Classification. David Wilson-Barlcer . . 



Notes AND News 



The Miocene Group of Alabama. Lawrence 

 C.Johnson 



The Scientific Aspect of the University Set- 

 tlement Movement. Frederic A. C. Per- 



A New Visual Illusion. Edmund C. Sanford. 

 A Suggestion as to Topographic Maps. Ar- 

 thur P. Davis. 



Letters to the Editor. 



Pseudoaurorge. George H. Hudson 93 



Continuous Rain. H. E. Chapin 94 



Natural Selection at Fault. Richard Lees.. 94 

 Leaf Impressions in tlie Eocene Tertiary of 



Alabama. Daniel W. Langdon, Jr 94 



Bowser's Mathematical Text-Books. A, S. 



Hathaway 95 



Some Additional Remarks on Maya Hiero- 

 glyphic Writing. Dr. Seler 95 



Languages of the Gran Chaco. Samuel A. 



Lufone Quevedo 95 



Controversies in Science. Edward P. Wil- 

 liams, Jr — 95 



Book Reviews. 



The Hemiptera Heteroptera of the British 

 Islands. Thomas R. R. Stebbing 96 



Entered at the Posi-OfBce of New York, N.Y., as 

 Spcond-OlaBa Mail Matter. 



THE AMERICAN RACE. 



By DANIEL G. BRINTON, M.D. 



*' The book is one of unusual interest and value. ^' — 

 Inter Ocean. 



" Dr. Daniel G. Brintonwrites as the acknowledged 

 authority of the subject.^''— Philadelphia Press. 



*' The work will be of genuine value to all who 

 wish to know the substance of what has been found 

 out about the indigenous Americans,''— iVatu7*e. 



*'A masterly discussion, and an example of the 

 successful education of the powers of observation." 

 —Philadelphia Ledger. 



Price, postpaid, $2. 



FOSSIL RESINS. 



This book is the result of an attempt to 

 collect the scattered notices of fossil resins, 

 exclusive of those on amber. The work is of 

 interest also on account of descriptions given 

 of the insects found embedded in these long- 

 preserved exudations from early vegetation. 



By CLARENCE LOWN and HENRY BOOTH 



13°. $1. 



N.:D. C. HODGES, 



874 Broadway, New York. 



IMPORTANT BOOKS. 



Craig— " LINEAR DIFFERENTIAL 

 EQUATIONS." Cloth, 8vo, 516 pp., $5. 



Ferrfl — "POPULAR TREATISE ON 

 THE WINDS." Cloth, Svo, 504 pp., $4. 



Barker — " DEEP SEA SOUNDINGS." 



3 maps, 8vo, cloth, $3. 



Gilbert- "DE MAGNETE." Translated 

 with extensive notes by P. F. Mottelay. 

 8vo, cloth, antique, $4. Sold by subscrip- 

 tion. Ready February 15. 



JOHN WILEY & SONS, 



Scientific Publishers, New York. 



TISEFUI. HAND-BOOKS. 



The Ornamental Penman's Pocketbook of Alpha- 

 bets, for sign-writers, engravers, stone-cutters and 

 draftsmen. SO els. A System of Easy Lettering, by 

 Howard Cromwell, 50 ots. Practical Electrics : A 

 Universal Handybook on Bvery-day Electrical Mat- 

 ters, 135 pp., fully illustrated, 12mo, cloth, 75 cts. 

 Notes on Design of Small Dynamo, by G. Halliday, 

 79 pp., with a number of plates to scale, 12mo, cloth, 

 $1. The Phonograph and How to Construct It, by 

 W. Gillett, 87 pp., 13 folding plates, ISmo, cloth, $3. 

 SPON & CHAMBERLAIN, Publishers, 12 Cortlandt 

 St., New York. Illustrated and descriptive cata- 

 logues, 10 cts. 



QUERY. 



Can any reader of Science cite 

 a case of lightning stroke in 

 which the dissipation of a small 

 conductor (one-sixteenth of an 

 inch in diameter, say,) has failed 

 to protect between two horizon- 

 tal planes passing through its 

 upper and lower ends respective- 

 ly? Plenty of cases have been 

 found which show that when the 

 conductor is dissipated the build- 

 ing is not injured to the extent 

 explained (for many of these see 

 volumes of Philosophical Trans- 

 actions at the time when Lo-ht- 

 ning was attracting the attention 

 of the Royal Society),, but not 

 an exception is yet known, al- 

 though this query has been pub- 

 lished far and wide among elec- 

 tricians. 



First inserted June 19, 189 1. No re- 

 sponse to date. 



H. D. C. HODGES, 874 BROADWAY, N. Y. 



SCIENCE 



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 ing scientific men and women of Amer- 

 ica and Europe have agreed to contrib- 

 ute to the paper during the coming year; and, 

 as others are constantly joining in this move to 

 make the paper more valuable than ever, it can- 

 not be long before there will be over tWO thou- 

 sand competent users of this weekly 

 medium of scientific discussion. 



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