x ] ORIGIN AND OPERATIONS 



on our own premises, the proprietor of an extensive garden in the immediate vicinity very 

 kindly permitted its use. On the 1st, llth, and term-days of each month, observations were 

 made there for the total horizontal force ; the inclination was observed on the first two days, 

 and the declination on that last named. When cither the 1st or llth fell on Sunday, the ob- 

 servations Avere made on the following day. On the term-day the changes of the declination 

 also were noted at short intervals, extending through 24 hours. These last observations were 

 under charge of Mr. Smith, who was occasionally aided by the Chilean students of astronomy. 

 Those for absolute elements during the first year were made by Lieut. MacRae and myself; 

 subsequently, the declinometer and dip circle were given up to Mr. Phelps. 



The meteorological instruments comprise a barometer of Hassler's construction, having an 

 internal diameter of six tenths of an inch ; standard thermometers by Troughton & Simms 

 and Jones ; self- register thermometers by the former artists, and a psychrometer by Bunten. 

 The Eeaumur scale of the last is divided on paper, and enclosed in a glass cylinder surrounding 

 the- tube, to which its lower extremity is joined by fusion. By the capillary action of a linen 

 cord, one of the bulbs was constantly supplied with water from a bird-glass. Some time after 

 the observations commenced, a spirit-register thermometer, divided on the tube to single de- 

 grees, was converted into a minimum wet-bulb, to which moisture was conveyed in a similar 

 manner as to the preceding. The barometer was suspended in a corner of the office-room ; all 

 the others within boxes open at bottom, and under the adjoining balcony on the south side of 

 the house. Observations were commenced in November, 1849, and, during the first year, were 

 continued throughout the day and night at intervals of three hours. Afterwards, the journal 

 was placed wholly under the charge of Mr. Smith, and the 3 A. M. observations were necessarily 

 omitted. Besides these tri-hourly records, there were hourly notations on the meteorological 

 term-day of each month, omitting the hours from 1 to 5 A. M., both inclusive, when Mr. Smith 

 was the only observer. The journal closes with September 13, 1852. 



Among the interesting notes with which it abounds, are those relating to the frequent earth- 

 quakes experienced. A general summary of these, together with such deductions as it was 

 possible to draw from observations, which the phenomena themselves almost incapacitate one 

 from recording properly, have been given in Chapter IV, Vol. 1, and allusion is made to 

 them here only because of their constant influences on the adjustments of our astronomical 

 instruments. At other observatories, the astronomer either finds the level, zenith-point, and 

 azimuth of his meridian instruments almost unchanged during weeks and months, or they are 

 subject to deviations following some general law of which the records of his meteorological 

 journal afford him satisfactory exponents, and his adjusting screws may remain untouched. 

 We dared not rely on the permanence of ours from the commencement to the close of a single 

 series of observations ; for, besides the shocks that vibrated walls, whose warning or accompa- 

 nying rumble started us into attention, there were an infinity of others to which man is physi- 

 cally insensible, but whose occurrences were quite plainly indicated by disturbances of the meri- 

 dian circle and clock. Multiplying work of a certain character, as these imperatively did, there 

 was less time for more interesting observations, and the verifications became greatly more 

 laborious. How excessive these disturbances were, may be judged of from the fact that the 

 earthquakes of one day retarded the clock ll|s., and changed the azimuth of the circle piers 5'. 



Our work in Chile was completed. Dr. Moesta had taken charge of the NATIONAL OBSERVA- 

 TORY on the 14th September; our original observations had been packed to go round Cape Horn, 

 and the copy remained to accompany me across Panama ; very cordial acknowledgments had 

 been tendered to the government for its unremitting courtesy, consideration, and assistance; a 

 most complimentary letter of leave had been received in reply, and there remained but to order 

 the assistants to the United States before embarking myself. The route of Lieut. MacRae had 

 been a subject of thought for some time. There was an interesting question in magnetism to 

 be solved, and many years might elapse before another equally favorable opportunity would 

 occur ; the geography and meteorology of the region he would traverse for these observations 



