Perusal of a late Publication by Mr. Babbage. 45 



in both of which I communicated the corrected lengths of the 

 pendulum, and the latitudes : and showed by their comparison 

 with those previously calculated, that the differences were 

 far too small to have any influence whatsoever on any of the 

 deductions in which those results had been or were likely to 

 be employed. That, in fact, for every practical purpose re- 

 garding the pendulum experiments in which the circle was 

 used, it was immaterial whether the divisions of the level were 

 considered as single seconds, or as 10*9 seconds each. 



Regarding the divisions as single seconds when observing 

 with the circle, I had deemed it of less consequence that the 

 readings of the level should be a precise record, than I should 

 have done had I known their true value. Satisfied if the 

 readings should approximate within limits which, as I be- 

 lieved, would not occasion error of greater amount than the 

 results were subject to from other causes, I made no comment 

 beyond the notice of the fact, being occasionally obliged to 

 employ the circle on supports that were not perfectly stable 

 or insulated ; such as on window sills, &c, such positions 

 being on those occasions the best within my command. For 

 the same reason I suffered myself greatly to underrate the 

 real disadvantage I laboured under, in not having, as is usual 

 in observations with a repeating circle, an assistant, whose 

 observation should be exclusively given to the level, and who 

 should read it simultaneously with [the observation at the te- 

 lescope, to which moment the reading should correspond. 

 Having both operations to perform myself, I was obliged to 

 attend to them in succession, and thus to read the level sub- 

 ject to such small alterations as the changes of my own posi- 

 tion or other causes might have occasioned in the interim*. 



I may here remark, that had I been acquainted with the 

 true value of the level at the time, I should still have em- 

 ployed the circle when I did ; for it was the best resource 

 I had, and was amply sufficient for the purposes of the 

 pendulum, for which alone I required its use. But I should 



* I had trained my servant, who had been with me in the northern 

 voyages, to render me the assistance alluded to, and other assistance of 

 the same nature : but I had the misfortune to lose his services at Sierra 

 Leone, my first station, by the fever of the country, from the effects of 

 which he ultimately died. Capt. Clavering, in his anxiety to promote the 

 objects in which I was engaged, endeavoured, as far as he was able, to re- 

 medy the loss, by supplying me with assistants chosen from amongst the 

 marines of his ship's company ; but after witnessing the deaths of five 

 men thus landed at different times for my assistance, I determined from 

 thenceforward to do the best I could alone, rather than obtain assistance 

 at such fearful risk to others. 



not 



