I. Meteoeology. 



1. Keep a journal of the Aveather at regular intervals of time, 

 noting — 



(1.) The direction of the Avind. 



(2.) Face of the sky as to cloudiness. 



(3.) Direction of motion of upper and lower clouds. 



(4.) Eain, snow, hail, fogs, &c. 



(5.) Temperature of air and Avater. 



(6.) Pressure of air. 



(7.) Moisture by wet and dry bulb thermometers. 



2. In recording any observation give the exact time, latitude 

 and longitude of ship, and name of the observer. 



3. When but two observations are made in the course of 

 the day the hours should be 8 a. m. and 8 p. m.; when 

 three observations, at 7 a. m., 2 and 9 p. m. If the number 

 of observers is sufficient a record of temperature and pressure 

 may be made hourly or bi-hourly for a week together when the 

 vessel is stationary, in order to ascertain the daily variations. 

 Unusual phenomena should be recorded at the time of occurrence. 



4. The indications of a maximum and also of a minimum 

 thermometer should be recorded at least once a day. 



5. The observations with the wet and dry bulb thermometer 

 are very important and should be cai'efully made at least three 

 times a day in a jilace freely exposed to the air. The difference 

 between the wet and dry bulb will be less in warm weather 

 when the air is nearly saturated with vapor, and also in cold 

 weather when it contains very little moisture. The wet bulb, 

 hoAvever, should ahvays be the loAver ; but in some cases during 

 a loAV falling temperature the AAater absorbed by the covering or 

 the wet bulb may become frozen, and Avhile evolving its latent 

 heat Avill prevent as a rapid a descent of the mercury as in the 

 ease of the dry bulb, Avhich may be at the time exposed to a cur- 

 rent of cold air. If the obser\^ation, however, be continued 

 sufficiently long and the temperature remain steady the covered 

 bulb Avill finally indicate the lower temjierature though it be 

 covered Avith a coating of ice. 



6. The force of solar radiation should be observed every day 

 at noon, with a blackened bulb thermometer, surrounded by a 

 vacuum, enclosed in an outer glass envelope. In default of tbi** 



