198 Instructions for Making and Registering [Jan. 



climate — or consider it, secondly, as the farthest extremity of one of 

 the two great lobes of land which form the terrestrial part of our globe, 

 and as such, constituting at once a barrier to the currents and tides of 

 two great oceans, and a limit to their climates — or, lastly, as a great 

 nautical station, and one not devoid of difficulty and danger, in which 

 every consideration of practical interest combines to stimulate the 

 curiosity of the theorist, and give importance to the results of his in- 

 quiries. 



.As these pages may fall into the hands of many who have been little 

 in the habit of observing systematically, or who may not be in posses- 

 sion of instruments of the nicest construction, attention to the follow- 

 ing instructions is recommended as the means of rendering their obser- 

 vations most available for useful purposes, and comparable with each 

 other, and, with those intended to be referred to as standards. 



I. General Recommendations and Precautions. 



1. The continuity of observations ought to be interrupted as little as 

 possible by changes in the adjustments of instruments — in their places 

 -—exposure — mode of fixing — or of reading off and registering them. 

 Whenever any alteration in these or any other particulars takes place, 

 especially such as are likely to affect the zero points, or otherwise to 

 influence the mean results, it should be noticed in the register. 



2. So far as possible, registers should be complete — but if by un- 

 avoidable circumstances of absence, or from other causes, blanks occur, 

 no attempt to fill them up by general recollection, or by the apparent 

 course of the numbers before and after, should ever be made. 



3. The observations should, if possible, all be made by one person— 

 but as this may often be impracticable, the principal observer should 

 take care to instruct one or more of his family how to do it, and should 

 satisfy himself by many trials that they observe alike. 



4. The entries in the register should be made at the time of observa- 

 tion, and the numbers entered should be those actually read off on the 

 respective scales of each instrument, on no account applying to them 

 previous to entry any sort of correction, as for instance for zero, for 

 temperature, capillarity, 8fC. All these and the like corrections, being 

 matter of calculation and reasoning from other observations, are to be 

 reserved till the final discussion of the series, and for separate deter- 

 mination and statement.* 



5. If copies be taken of the registers, they should be carefully com- 

 pared with the originals by two persons, one reading aloud from the 

 original and the other attending to the copy, and then exchanging 

 parts, a process always advisable wherever great masses of figures 

 are required to be correctly copied. 



J We regard this as of the highest importance. 



