A WEEKLY ILLUSTRATHU JOURNAL OF SCIENCE 



"To the solid ground 

 Of Nature trusts the mind -which builds for aye." — Wordsworth 



MACMILLAN & CO., Publishers, 22 Bond St., NEW YORK. 



Vol. 21 

 No. 13 



THURSDAY, JANUARY 29. 1880. j 



Price 15 Cents 

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LECTURES AND ESSAYS. 



BY THE I. All. 



WILLIAM KINGDON CLIFFORD, F.R.S , 



I.ati and Afechunics in University College, London, 



ome time Fellow of Trinity College, Cam 



Edited by LESLIE STEPHEN and FREDERICK POLLOCK, with an Introduction by F. 

 POLLOCK. Two volumes, 8vo, 37.50. 



" In the region of pure matheuu tic . he was one of the first five or six original thinkers in Europe. As an expounder to 

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acter that he is seen in the volumes that are now before us — a collection of such of his papers and lectures as were 

 addressed to non-technical audiences." — London Saturday Rev, 



SEEING AND THINKING. 



BY THE LATE 



WILLIAM KINGDON CLIFFORD, F.R.S. 



Forming the New Volume of the NATURE SERIES of Scientific Works, umo, $1. 



CONTENTS.— The Eje and the Brain— The Eye and .Seeing— The Brain and Thinking— Ol 

 Boundaries in General. 



UNITS AND PHYSICAL CONSTANTS. 



By J. D. EVERETT, M.A., D.C.L., F.R.S., etc., Professor of Natural Philosophy 

 In Queen's College, Belfast. i6mo, $1.10. 



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