368 EXPEDITION TOWARD THE NORTH POLE- 



unreliable after the first sis months, it will be necessary to have recourse 

 to lunar^distauces. These should be measui-ed from the sun, in prefer- 

 ence to a star, whenever it is practicable to do so. 



If a sextant is used in observation, a measure of the semi-diameter of 

 the sun or moon should be taken every day or two for index error. 



The observations are by no means to be pretermitted when lying in 

 port, because they will help to correct the position of the port. 



The observations should, if convenient, be taken so near the standard 

 chronometer that the observer can signal the moment of observation to 

 an assistant at the chronometer, who is to note the time. If this is not 

 found convenient, and a comparing watch is used, the watch-time and 

 the comparison of the w^atch with the chronometer should both be care- 

 fully recorded. 



The observations made by the main party should be all written down 

 in full in a continuous series of note-books, from which they may be 

 copied in the log. Particular care should be exercised in always recording 

 the place, date, and limh of sun or moon observed, and any other particu- 

 lars necessary to the complete understanding of the observation, 



S. NEWCOism. 



Ohservatmis at winter quarters. — The astronomical transit instrument 

 will be set up in a suitable observatory. A meridian mark should be 

 established as soon as practicable, and the instrument kept with con- 

 stant care in the vertical plane passing through the mark, in order that 

 all observations may be brought to bear on determining the deviation 

 of that plane from the meridian of the places. The transits of circum- 

 polar stars, on both sides of the Pole, uud those of stars near the Equa- 

 tor, should be frequently observed. 



Moon culminations, including the transits of both first and second 

 limbs, should be observed for the determination of longitude independ- 

 eutly of the rates of the chronometers. Twelve transits of each limb is 

 a desirable number to obtain— more, if practicable. If any occulta- 

 tious of bright stars by the moon are visible, they should be likewise 

 observed. 



The obser^•ations for latitude will be made with the sextant and arti- 

 ficial horizon, upon stars both north and south of the zenith. 



All the chronometers of the expedition should be compared daily, as 

 nearly as practicable about the same time. 



Whenever a party leaves the permanent station for an exploration, 

 and immediately upon its return, its chronometer should be compared 

 with the standard chronometer of the station. 



Ohservations during sledge or boat journeys.— The instruments to be 

 taken are the small Casella theodolite, or a pocket sextant and artificial 

 horizon, one or more chronometers, and a prismatic compass, for taking 

 magnetic/bearings of the sun. In very high latitudes the time of the 

 sun's meridian altitude is not readily determined ; it will be advisable, 



