lON TO I'OINT I'.AIMJ )\V. ALASKA. H 



Xo. L'S. Precipitation. The commencement and duration of rain, MIOW, hail, &(.. and. when 

 possible, the amount of piecipilation, is to be ol.x-i veil. As to tin- anioiuit. howcvei. this is nut 

 obligatory in winter. 



| There will lie recorded regularly, and, it' practicable, hourly, tin- amount of precipitation, 

 measured if pos.-ihle, otherwise estimated. | 



No. !'!>. The trctitlici: Stoinis, thunder-storms, hail, log. Irost, dew, &<.. and the ojr 

 phenomena of the atmosphere ought to l>e recorded. 



2. OJJI.lC.VrolM OiiSKltVATlONS IN Till; IX. MAIN nl-' TF.i: I; F..S M; I \ I 



"No. oil. Absolute determinations. For declination and inclination it is necessary to attain an 

 iiccnracy of 1.0 minute, for horizontal intensity of 0.001. The proper instruments an-, lor 

 example, the portable theodolite of Lamoiit and (lie ordinary dip-needles. 



No. ">!. The absolute observations must be executed in close connection and synchronous 

 with the readings of the variations instruments, in order to be able to reduce the data given by 

 the latter to an absolute normal value, and to determine the xero point of the scale.-. The 

 determinations must be made so frequently that the changes in the absolute value of the zero 

 point of the scales of the variations apparatus can be accurately checked thereby. 



No. 3l!. Observations of nirintioins. These ought to include the three elements and be made 

 by means of instruments, with small needles, in contrast to the apparatus of Causs. In order to 

 obtain an uninterrupted reciprocal control, two complete .sets of variations instrumenls are 

 desirable, and recommended, in order to avoid any interruption of the observations, by reason 

 of breakage, derangement, \-c. 



[One set of these instruments is now provided, but a second set may be sent in I> 



Xo. 33. The horizontal intensity in one, at least, of these systems should be observed with the. 

 unililar apparatus. Jiecaii.se of the. magnitude of the perturbations to be observed, the scales of 

 the variations instruments must have at least a range often degrees, and the arrangements are to 

 be so made that the greatest possible simultaneity of the readings may be achieved. 



Xo. 34. During the entire period of occupancy of the station the variations instruments will bo 

 read hourly. It is desirable that two readings be made: for instance, just before and after the full 

 hour, with an interval of a lew minutes between. 



Xo. 3~>. Weyprecht presented the following separate note on this point: 



" Since it appears to me that in these regions of almost perpetual disturbances, hourly readings, 

 made at moments not well defined, are insufficient to establish mean values accurately expressing 

 the local perturbations for a given epoeh (which data ought to serve as a means of comparison 

 with other localities), and in consideration of the slight increase of labor which will be caused by 

 taking readings at precise moments, I cannot agree with the views of the majority of the Confer- 

 ence/' 



I state that at least the expedition conducted by myself will take readings hourly of all tbreo 

 vacations instruments at 5S 1 " <K .~> ( .l" ! (V; 00'" s ; 01'" <)*; CL"" O a : (lottingen mean time." 



"WEYPKEOHT." 



[Observations will be taken as specilied by Weyprecht. | 



No. 3G. As term days, the first and fifteenth day of each month will be observed from midnight 

 to midnight, Ciottingen time. The readings will be 'alien at intervals of five minutes, always on the 

 full minutes, and the three, elements.are to be read with all possible rapidity, one after the other, 

 in the, following order : 1. Horizontal intensity : L'. 1>; clination : 3. Vertical intensity. 



Xo. 37. For these term days, the plan of magnetic work should comprehend continuous read 

 ings, for instance, readings every twenty seconds throughout one whole hour even though only 

 one magnetic element be observed. It is the opinion of the Conference that the observations 

 should begin so that one of the hours of observation shall agree with the first hour of the 1st of 

 January, and that during the en tin- period of magnetic work the hours de\oted to this continuous 

 observation should bechanced on each successive semi-monthly term day. 



Tor x[>i>ci;il instructions in magnetic' work, fiirnUheil l>y Ilio Siii>ri'intoialc.-iit "I" tlir I'liiti-d Slat,'* Count and 

 Survey, nee S-riion ]V of these instructions. 



