568 [May 21, 



thermal lines are represented between the latitudes of 5 N. and 36 

 W., and longitudes of 78 E. and 98 E. of Greenwich. 



1st, of the mean temperature of the year; 



2nd, of the cool season, viz. December, January, and February ; 



3rd, of the hot season, viz. March, April, and May ; 



4th, of the rainy season, viz. June, July, and August ; 



5th, of the autumn, viz. September, October, and November. 



The memoir which accompanies the Plates contains a statement of 

 the data on which the isothermal lines are founded. 



These are : 1 . Meteorological researches made by the author and 

 his brothers at various stations in India and the Indian Archipelago 

 during the years 1854-1858. 



2. The original manuscripts in thirty-nine folio volumes of meteo- 

 rological observations made by various observers under the authority 

 of the Indian Government at 207 stations in British India. In regard 

 to the observations referred to under this head, the author considers 

 that he possesses a special qualification for using them advantageously 

 by having himself visited most of the stations, examined the instru- 

 ments, and acquainted himself with the circumstances of their em- 

 ployment. 



The 207 stations are divided into ten geographical groups, as 

 follows : 



1. Eastern India : 1, Assam ; 2, Kharsia Hills 12 



2. Bengal andBahar, and Delta of the Ganges and Brahma- 



putra 36 



3. Hindostan, the upper Gangetic plain 27 



4. Panjab, including the stations west of the Indus 24 



5. Western India : Rajvara, Guzrat, Kach, Sindh 10 



6. Central India : Berar, Orissa, Malva, Bandelkhand .... 15 



7. 1, Southern India : hilly districts, Dekhan and Maissur; 



2, Nilgiris 29 



8. Southern India, coasts : K6nhan, Malabar, Karnatik . . 24 



9. Ceylon 



10. Indo-Chinese Peninsula, Archipelago, and China .... 20 

 Each group has its appropriate processes of reduction, which are 



severally discussed. 



