206 S. A. Hill. — The Psychrometer and tlie condensing Hygrometer. [Nov. 



The following papers were read : 



1. On certain features in the Oeological Structure of the Myelat 

 District of the Souther7i Shan States in Upper Burmah as affecting the 

 drainage of the country.— By Brigadier General Collett, 0. B. Coyn- 

 municated hy Dr. D. D. Cunningham. 



2. The Psychrometer and the condensing Hygrometer. — By S. A. 

 Hill, Esq., B. Sc, Meteorological Reporter to the Government of the 

 N. "W. Provinces and Oudh. 



[Received October 12tli.] 



(Abstract.) 



After a" description of Regnanlt's condensing hygrometer and a 

 justification of the assumption that the thermometer immersed in the 

 ether has sensibly the same temperature as the surface on which the 

 dew is deposited, the author goes on to discuss the results of an exten- 

 sive series of comparative observations of the two instruments made by 

 him this year, together with those of a shorter series made in 1881. 

 Amongst the observations are some made under extreme conditions of 

 heat and drjmess, the dew point in one instance having been 74*5 degrees 

 below the temperature of the air. 



The conclusion arrived at is that it is unlikely that Regnault's mo- 

 dification of August's formula for reducing psychrometric observations 

 will be improved upon ; but that whilst the formula gives results which 

 approximate very closely to the truth when the air round the thermo- 

 meter is stirred by a moderate wind, the deduced humidity is consider- 

 ably too high in a calm state of the atmosphere. 



It is incidentally proved also that any method of reduction which 

 assumes that the indications of the psychrometer are independent of 

 barometric pressure, as do Glaisher's factors and a table recently con- 

 structed by Hazen, must give erroneous results except at places situated 

 near sea-level. 



3. Anopolophrya seolosomotis, a new Giliate Infusorian parasitic in 

 the alimentary canal of -^olosome chlorostictum.— J5?/ Henry H. 

 Anderson, Esq. 



4. Some neio forms of Euplotes found in Calcutta Tanks. — By 

 Henry H. Anderson, Esq. Communicated by the Microscopical Society. 



5. The Butterflies of the Nilgiri District, South India. — By G. F. 

 Hampson, Esq., B. A., Exeter Coll., Oxford. Communicated hy The 

 Superintendent of the Indian Museum. 



6. Pseudopulvinaria Sikkimensis, a new genus and species of Coc- 

 cidae /rom Sikkim. — By E. T. Atkinson, Esq., B. A. 



