During the month of April in the year 1855, the following letter appeared in the pages of "The Photographic and Fine Art Journal" (April 1855) pages 124-125: - - - - - - - - - DAGUERREOTYPING ON THE ROCKY MOUNTAINS. New York, March, 20 1855. To H. H. SNELLING ESQ. DEAR SIR:--I am very sorry I am unable to respond to your request for the particulars of my tour with Colonel J. C. Fremont, in his late Exploring Expedition across the mountains, not having taken any private notes. But this much I am at liberty to say that I succeeded beyond my utmost expectations in producing good results and effects by the Daguerreotype process, on the summits of the highest peaks of the Rocky Mountains, with the thermometer at times from 20 to 30° below zero, often standing to my waist in snow, buffing, coating, and mercurializing plates in the open air.--In nearly every instance Barometrical, and Thermometrical observations were obtained at the same moment, with the picture. The time given to each example was also noticed and marked on the plate. I requested permission from Col. Fremont who readily afforded the means to make these observations, and they may account for the very great difference of time, which it took to make pictures, under apparently the same combination of circumstances. All these observations have been carefully noted and will be published for the benefit of the scientific world, in Col. Fremont's forthcoming Journal, which these pictures will serve in some measure to illustrate. I had considerable trouble with the iodine, which under ordinary circumstances requires 80° Fht. before it will part with its fumes. I had to use artificial heat in every instance, I found it necessary to make up in quantity for the loss of temperature. I generally employed Anthony's Anhydrous sensitive, and my boxes during a continual use of five months only required replenishing four time, notwithstanding they were opened every time I made a picture, to arrange it smoothly at the bottom. The coating boxes were made expressly for my use on the Expedition by E. Anthony Esq. And I cheerfully recommend the use of similar ones for like purposes. Notwithstanding the earnest prognostications of yourself and my professionals friends, both in New York and Philadelphia, that under the difficulties I was likely to encounter on the snow capped mountains,--I would fail, I am happy to state that I found no such word in my vocabulary although I had not much youthful, or physical strength to bring into the scale. I am Dear Sir yours truly. S. N. CARVALHO. -------------------------------------------------------------- 04-22-99