DISCUSSION OF THE BAROMETRIC OBSERVATIONS OF PROF. E. S. 

 SNELL (AMHERST COLLEGE). 



By Prof. F. H. Loud, of Colorado College. 



The meteorological register of Amherst College was begun in 1835 

 by the late Prof. E. S. Snell, and consisted for the first year of a mere 

 register of storms, to which daily observations of the thermometer and 

 wind were added in 183G. Barometric observations were also begun in 

 November, 183G, but the instrument employed for the first fifteen years 

 was of inferior accuracy, and the observations were not corrected for 

 capacity nor for temperature. With the beginning of the year 1852, 

 new instruments by James Green — a barometer, thermometer, and psy- 

 chrometer — were furnished by the Smithsonian Institution, and in 1854 

 the uniform hours of observation recommended by the Institution were 

 introduced. The thermometer previously in use was at the same time 

 tested and approved by Professor Guyot. From that time to the present 

 the same instruments, with the exception of one bulb of the psychrom- 

 eter, have been in use iu the same positions ; and, together with gauges 

 for rain and snow, they comprise all the instruments used in the daily 

 observations. From the same time the hours of observation have re- 

 mained unchanged, viz, 7 a. m. and 2 and 9 p. m. The series of twenty- 

 five years of observations, from 1851 to 1878, is therefore as nearly as 

 possible homogeneous throughout, and it is scarcely less so in respect 

 of the observers who have been engaged upon it, for few of the observa- 

 tions have been made by others than Professor Snell and one or two 

 members of his family. His well-known scrupulous accuracy is there- 

 fore characteristic of the whole work. In 1858 five months of observa- 

 tion were made by the tutor in mathematics (now Rev. H. S. Kelsey, of 

 Xew Haven) at his room in North College, the only instance of a removal 

 of the instruments ; but before the barometer observations made during 

 this interval were incorporated with the others in the present reduction 

 they were corrected for difference of level, no such correction having been 

 made at the time. 



Amherst is situated in latitude 42° 22', longitude 72° 30' W. The 

 elevation of the barometer-cistern above the level of the sea was deter- 

 mined by Professor Guyot at 267 feet, and this computation has been 



