OP THE EXPEDITION. V 



our northern ports. It being inhabited by a civilized and most hospitable people, would tend 

 to render a residence of five or six months in the latter part of the autumn and winter not 

 altogether uncomfortable. Its distance is about 5,000 miles due south from Washington; and 

 a comparison of the observations I proposed to make there with those to be obtained at the 

 Washington observatory, would give us a determination of the parallax from data wholly 

 American. This last reason I hoped would benefit me, should it be necessary to seek the inter- 

 position of Congress. 



On the 9th November following, I wrote Dr. Gerling more at length, telling him : "When 

 I proposed to you, on the 25th July last, an expedition to the island of Chiloe, for the purpose 

 of making, between the stationary terms of Venus in 1849, nearly simultaneous observations 

 with those of the Washington observatory on that planet, and from them to determine the solar 

 parallax more acciirately, as pointed out in your letter of 17th April last, my anticipations 

 were limited to the results that a tolerably skilful and well equipped traveller might be expected 

 to contribute to astronomical science, and my chief reliance was intended to have been on differ- 

 ential micrometer observations. Since then I have had leisure to reflect on the importance of 

 the undertaking, and, remembering the vast outlays Europe has encountered in efforts for the 

 faithful solution of this very problem, as well as in other hundreds of scientific enterprises, and 

 the fact that America, which participates so largely in the benefits derived from the labors of 

 astronomers, has hitherto contributed so trifling an amount to the common stock, I am the 

 more keenly sensible of the noble opportunity now within our grasp to present the world, from 

 our own continent as a base, the dimensions of our common system. 



"I hope my desires may not 'prove father to the thought;' but the more I consider the sub- 

 ject, the more firmly am I impressed with the belief that the able minister who has for a length 

 of time presided with universal approbation over the affairs of the navy will not now falter in 

 interest for its advancement, but will hail the occasion offered, and add a new laurel to the 

 chaplet of its renown, a gem to the national diadem. There is but one perceptible obstacle 

 pecuniary outlay ; yet when its very inconsiderable amount is contrasted with the grandeur and 

 importance of the object to be attained, I cannot bring myself to believe that this objection will 

 be suffered to weigh, and I therefore repeat the remark made in my former letter give the 

 proposition the encouragement of scientific men, and I stand pledged for its successful equip- 

 ment. At all events, regarding it as a possible attainment only, two questions present them- 

 selves for consideration, and it is time they were discussed : first, Is the locality proposed 

 (Chiloe) the best which can be selected for the contemplated object? and, second, Will the 

 instruments which have been specified to you permit the accomplishment of that object in the 

 most satisfactory or desirable manner ? 



"America offers greater advantages to observatories lying on the same or nearly the same 

 meridian than any other country its greatest length being north and south. Deeming a 

 station on this continent of paramount consequence, for the reason already mentioned, that it 

 may be a contribution from the New to the Old World, as cceteris paribus the amount of the 

 probable error of the parallax observed will be proportional to the length of the terrestrial base, 

 it is evidently important that the stations from which observations are to be made should be 

 separated as widely as possible. Now, the northern observatories are already established, 

 therefore it becomes desirable that the southern station be made as near to the extremity of the 

 continent as circumstances will justify ; and these circumstances are, climate, accessibility, and 

 means of sustenance for the observers during their residence. 



" On the first of these points I transcribe somewhat at length the information gathered from 

 various writers on Chile respecting the island named, I now fear too hastily. An islet (Caylin) 

 near its southern shore is called by the natives 'la fin de la crisliandad.' If the name have 

 meaning, as, in the sequel, you will probably have cause to believe, even did the climate per- 

 mit, it would not be possible to establish an observatory farther south than Chiloe, without a 

 special ship to convey and take off the observers and their means of sustenance, because it would 



