990 



sidered as in reality due to a transformation or conversion of heat 

 by its passage through an organized structure ; just as heat, acting 

 through a certain mixture of metals, manifests itself as electricity. 

 Hence he concludes that the physical forces are as closely corre- 

 lated to the vital, as those of each category are to each other ; the 

 chief distinction between their respective operations being esta- 

 blished by the speciality of the instruments through which they 

 manifest themselves. 



13. Letter from Lieut. Gillies, U.S.N., to Lieut.-Col. Sabine, R.A., 

 For. Sec. R.S. 



U.S.N. Astronomical Expedition, 

 Santiago de Chile, 20th Jan. 1850. 



Dear Sir, — I had the pleasure to receive your letter of Aug. 3rd 

 by the last monthly steamer from the north, and greatly lamented 

 I could not answer it by the mail, which left Dec. 30th. Leaving the 

 United States on the 1 6th of August, want of a proper amount of fire 

 surface in the boilers of the steam-ship, caused my arrival at Chagres 

 only on the day (27th) when the mail for Chile left. A month was 

 thus unavoidably lost; for in anticipation of a passage through 

 without delay, all instruments, except an aneroid barometer and 

 thermometer, had been despatched round Cape Horn. With these 

 such observations were made, until arrival here, as their construction 

 permitted. From the indications of the aneroid there is a region 

 extending from 200 miles to the S.S.W. of San Domingo to about 

 1° of north latitude on this side of the continent, where the pressure 

 rarely exceeds 29*850 in., nor was the barometer but once in that 

 whole distance as high as 29'900 in. At Panama the mean is 

 29*795 in. from observations at 9 a.m., 3 p.m., and 9 p.m., with a 

 mean diurnal fall from the first to the second hours of '08 in. The 

 temperature for the same hours was 81°-0 with a range of 2°'9, and 

 almost constantly saturated with moisture, though rain fell no more 

 frequently than often occurs during the same period in the United 

 States. As evidence of the hygrometric condition of the atmosphere, 

 it was found impossible to dry clothing in my room after several days' 

 open exposure, and they were finally exposed to the direct rays of 

 the sun. Leather moulds in forty-eight hours. The light wind 

 experienced was almost constantly from the northward and west- 

 ward during the day, and variable at night. I think Lieut.-CoL 

 Emery made observations for declination and dip en route for Cali- 

 fornia, but nothing is known to me of the results, and I must await 

 our return to give you data on these points. Should nothing inter- 

 vene to change present intentions, I contemplate making observations 

 at each of the fifteen ports where the steamer touches between Valpa- 

 raiso and Panama. Nothing of note occurred during our passage 

 to Chile. There was time to glance at Buenaventura, Guyaquil, 

 Payta, Huanchaco (part of Truxillo), Casma, five days at Lima, 

 Pisco, Islay, Arica, Iquique, Coleiga, Copiapo and Coquimbo, — a 

 multitude of little towns unimportant in themselves, and mentioned 



