1891.] 



Presents. 



233 



The determination of the colours in Maxwell's disks by this plan 

 enables them to be used much more effectively than if they are 

 simply indeterminate colours. For since the sum of the luminosities 

 of any colours is equal to the luminosity of the same colours 

 integrated, it follows that when using the disks the colours of the 

 dominant wave-lengths are really mixed and the white light inherent 

 in each case can be deducted. 



Presents, February 19, 1891. 

 Transactions. 



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The Museum. 

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Giessen : Universitat. Akademische Schriften- 1887-1889. 8vo 



and 4to. Giessen. The University. 



Heidelberg: Universitat. Akademische Schriften. 1888 1890. 



8vo. Heidelberg. The University. 



Kiel : Universitat. Inaugural-Dissertationen. 1887-1890. 8vo 



and 4to. Kiel, Sfc. The University. 



London : Pharmaceutical Society of Great Britain. Calendar 



1891. 8vo. London. The Society. 



Royal Agricultural Society of England. Journal. Ser. 3. 



Vol. I. Part 4. 8vo. London 1890. The Society. 



Royal United Service Institution. Journal. Vol. XXXV. 



No. 156. 8vo. London 1891. The Institution. 



Louvain : Universite Catholique. Publications Academiques des 



Aunees 1887-1890. 8vo. Louvain. The University. 



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moires. [Russian.] Tomes X XI, XIV. (Partie 2.) XV. 



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d'Auteurs des Articles contenus dans les Series des Bulletins 



1886 a 1888. 8vo. Paris 1890. The Society. 



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1887-1890. 8vo a,nd 4to. Rostock. The University. 



Tiibinsren: Universitat. Inaugural-Dissertationen 8voand4to. 



[Various dates, 1848-1888.] The University. 



B 2 



