GENERAL REMARKS, 37 



interesting to astronomers, and if it would not much derange 

 her operations, she should be taken to some convenient ancho- 

 rage for the purpose of landing the instruments. 



" If a comet should be discovered while the Beagle is in 

 port, its position should be determined every night by observ- 

 ing its transit over the meridian, always accompanied by the 

 transits of the nearest known stars, and by circum-meridional 

 altitudes, or by measuring its angular distance from three well- 

 situated stars by a sextant. This latter process can be 

 effected even at sea, and the mean of several observations may 

 give very near approximations to its real position. 



. " Meteorological Registers may be of use in a variety of 

 ways ; but then they must be stetidily and accurately kept. 

 The barometer should be read off to the third place of decimals, 

 and recorded at regular periods of the day ; nine o'clock and 

 four o'clock may be recommended as the best, as being the 

 usual hours of its maximum and minimum. The temperature 

 should be marked at the same time, and the extremes of the 

 self-registering thermometer should be daily recorded; care 

 being taken that no reflected heat should act on any of these 

 instruments. The temperature of the sea at the surface ought 

 to be frequently observed and compared with that of the air. 

 An officer cruizing on the east coast of South America, be- 

 tween the parallels of 20° and 35°, was enabled by these means 

 to predict with singular precision the direction and strength of 

 the current. 



" In this register the state of the wind and weather will, of 

 course, be inserted; but some intelligible scale should be 

 assumed, to indicate the force of the former, instead of the 

 ambiguous terms ' fresh,"* ' moderate,' &c., in using which no 

 two people agree; and some concise method should also be 

 employed for expressing the state of the weather. The sugges- 

 tions contained in the annexed printed paper are recommended 

 for the above purposes, and if adopted, a copy should be pasted 

 on the first page of every volume of the log-book ; and the 

 officer of the watch should be directed to use the same terms in 

 the columns of the log-board. 



