274 OBSERVATORY AT CORDOBA, ARGENTINE REPUBLIC. 



haudvS in the " jSTaotical Almanac." Still, it was manifestly desirable, 

 and thus the work was arranged. Whenever possible, we observed, 

 each night, three zones with their belongings, which consumed about 

 eight hoars — often more. The zones averaged about a hundred minutes 

 in length : more than this strained eye and nerves too much. 



It is an exhausting process to lie for this length of time with the eye 

 glued to the telescope — one hand signaling the instants of each star's 

 transit over a group of delicate threads, and the other pointing the tele- 

 scope by means of a long screw-handle, estimating, at the same time, 

 the magnitude, and calling out the data to be recorded — the udgmeut 

 being meanwhile kept in active exercise for deciding upon the best 

 order in which to observe the various stars which are within view at 

 once, and the telescope kept in motion over the whole width of the zone, 

 (which is many times wider than the field of view,) in order that as 

 few stars as possible shall pass unobserved. In many zones we thus 

 observed more than 260 stars ; in one there were 285, an average of one 

 star to every twenty-one seconds. S'or is the labor much less for the 

 assistant at the microscope. He must be on the alert to measure and 

 record the reading of the graduated circle as soon as the telescope is 

 pointed ; must record the magnitude and groups for each star, as well 

 as the approximate moment from the clock-face, to prevent danger of 

 confusion when his record comes to be combined with that upon the 

 chronograph. And, what is more, he must watch the various pieces of 

 apparatus to see that nothing goes amiss, for chronographs will run 

 down, pen-points will clog and cease to mark, and telegraphic connec- 

 tions will sometimes give out; and when they do, it is always at some crit- 

 ical moment. The quickness and dexterity which the assistants acquired 

 was a source of astonishment and delight to me ; and, should our results 

 prove to be what I hope and believe they will, there is no one of the 

 iive gentlemen who have at different times taken part in this labor, 

 who may not feel a just pride, not only in the conscientious fidelity with 

 which he performed his part, but also in the skill which he attained in 

 most difficult operations. 



A full night's work consisted of three zones, with four series of obser- 

 vations for instrumental corrections. All the zones, and the last series 

 of determining stars, I observed myself; and, until the last few months, 

 the first series also. Between the zones I gave rest to my eyes. The 

 remainder of the work was distributed, as well as might be, among 

 three assistants, in such a way that each should be able to rest his eyes 

 for about an hour and a half on the nights of greatest labor, and also 

 have each third night free. But there was a period of six or eight 

 weeks when our force was temporarily reduced, so that the aid of 

 Messrs. Thome and Bachmann was needed every night. I need not 

 add that just at this time we had a spell of exceptionally clear weather, 

 with only two cloudy nights in a whole month. But there was not the 

 shadow of a complaint, nor was labor ever more cheerfully or cordially 



