508 A BRIEF ACCOUNT OF OUR WORK. 



cheerfully assuming certain hours of the twenty-four, in order to preserve the continuity of the 

 journal. The magnetical observations were less frequent, "but much more laborious ; occupying 

 nearly four hours of two, and sometimes three persons, on the 1st, llth, and term-day'*' of each 

 month, when all the elements necessary for determining the direction and total force of the earth's 

 magnetism were carefully observed. Other observations for changes of the Declination or 

 Variation, as it is generally called- were made at brief intervals throughout the term-day and 

 on the 1st of each month, during a pre-appointed hour, for the purpose of determining how 

 nearly synchronous might be disturbances in the northern and southern hemispheres. Those of 

 the northern hemisphere were conducted under the direction of the United States Coast Survey- 

 As the iron bars protecting the windows of all houses in Chile made it necessary to leave our 

 residence, when observing for absolute elements, we were kindly permitted to use a large garden 

 in the neighborhood, where arbors and shade-trees afforded suitable protection from the sun. 



There was yet one other subject for whose intelligent discussion it was hoped we might col- 

 lect interesting materials, and for which a rude instrument had been brought to assist us ; I 

 mean that startling terrestrial phenomenon of whose coming no man knoweth the earthquake. 

 With friends this was talked of as one of the physical wonders of Chile ; one that invested it 

 with rare interest for the geologist with constantly recurring terrors for the inhabitants. Nor 

 was our curiosity to experience a shock long ungratified, for within a week there was a tremor 

 that hurried the population to the streets. But we were novices, and moved not. To us it was 

 merely a spasmodic thrill, followed by a subterranean rumble whose moral influence lasted but 

 the moment. The seismometer, erected forthwith, soon had its powers tried ; but it could not 

 be rendered sufficiently sensitive, and made no record of the slight agitations which the earth's 

 crust almost daily underwent. This only increased our longing for information, and we 

 earnestly desired repetitions, straining every sense at each to gather facts that might become 

 available. Nor was it until the convulsion of December 6, 1850, that we could comprehend the 

 constant dread shown of the power beneath us, the alarm which each tremor flashed through 

 the population. When that of April 2d took place, and the earth, rocking to its very centre, 

 stifled all human sounds with its groans of agony, we were thoroughly converted to the custom 

 of the country to flee at every coming murmur; and though thirsting for knowledge still, we 

 no longer cared to acquire it under circumstances so shocking. What it was possible for the 

 mind to grasp in moments so trying and brief, has been detailed in Chapter IV, PART I, and in 

 Appendix A, where the reader may find facts of interest. All the other observations mentioned 

 are in process of reduction, and will be published in the several volumes as rapidly as practicable. 



We had scarcely organized work systematically before it was intimated to me, from the Uni- 

 versity, that the government would probably establish a national observatory at our departure, 

 and to this end was desirous to have one of the professors of mathematics, and two of the most 

 advanced and promising students of the National Institute, acquire a practical knowledge of 

 instruments. The utility of such an establishment, and the honor it would reflect on the 

 country, had been urged by the Chilean ambassador at Washington prior to our departure from 

 the United States ; and it was a source of no little gratification to me to witness the incipient 

 step promptly taken towards the realization of an object so noble. Of course assurance was im- 

 mediately given that no effort of mine or my companions, nor any facilities we could afford, 

 should be wanting for the accomplishment of any object the government might have in view. 

 When officially notified by the Minister for Foreign Affairs that three gentlemen had been 

 designated whom his government desired to place under my instruction, occasion was taken to 

 express to him how greatly gratified astronomers of the northern hemisphere would be at this 

 evidence of Chilean advance to the rank of enlightened and liberal nations. Very shortly after- 

 wards the students were presented by the rector of the University; books, from which to obtain 



* A pre-selected day, on which all magnetical observers note the changes of the elements at brief intervals. These days 

 commence at 10 p. M., mean time Gottingen, on the Fridays preceding the last Saturdays of February, May, August, and 

 Is'oveniber, and on the Wednesdays nearest the 21st of each of the other months. 



