24 



WRITINGS OF JOSEPH HENRY. [1855- 



assigned to the surgeons, at the suggestion of Surgeon Gen- 

 eral Lovell, was that of keeping a diary of the weather, and 

 of the diseases prevalent in their vicinity. The earliest reg- 

 ister received, under this regulation, was in January, 1819. 

 The only instruments at first used were a thermometer and 

 wind-vane, to which in 1836, a rain-gauge was added. The 

 observations were made at 7 a. m. and 9 p. m., and the winds 

 and weather were observed morning, noon, and evening. It 

 is to be regretted that in 1841, the variable hour of sunrise 

 was substituted for that of 7 a. m., since the latter admits of 

 an hourly correction which cannot be applied to the former, 

 except at the expense of too great an amount of labor. 



The results of the observations for 1820 and 1821 were 

 published at the end of each year ; those from 1822 to 1825, 

 inclusive, were issued in the form of a volume by Surgeon 

 General Lovell ; those from 1826 to 1830, and from 1830 to 

 1842, inclusive, were prepared and published in two vol- 

 umes, under the direction of the present Surgeon General, 

 Dr. Thomas Lawson. At the commencement of 1843 an 

 extension of the system was made by the introduction of 

 new instruments, and an additional observation to the num- 

 ber which had previously been recorded each day, and hourly 

 observations for twenty-four hours were directed to be taken 

 at the equinoxes and solstices. 



During the past year a quarto volume has been published, 

 which contains the results of the observations of the ther- 

 mometer, direction and force of winds, clearness of sky, and 

 fall of rain and snow, during a period of twelve j'ears, from 

 the first of January, 1843, to January, 1855, arranged in 

 monthly tables and annual summaries. To these are added 

 consolidated tables of temperature and rain for each separate 

 station, comprising the results of all the thermometric ob- 

 servations made by medical officers since 1822, and of all 

 measurements of rain and snow since the introduction of 

 the rain-gauge in 1836. 



The tabular part of this volume contains the most impor- 

 tant results of the observations of the army system of regis- 

 tration, and will be considered the most valuable contribu- 



