Frémont's Long Camp near Carson Pass
Voucher No. 4, 27 Feb. 1839, U.S. to E & G. W. Blunt, for a "camera lucida.". This simple optical device was a sketching aid. A lens and prism (or mirror) brought the image to the artist's tracing paper at the focal plane. Neither Frémont nor Preuss mention the actual use of the camera, but it is supposed that it was used from further purchase vouchers. Voucher No. 19, May 1842, U.S. to William King, Jr. for a "mirror for camera obscura" and "portable box to form the above". A similar device enclosed in a box using a reflex mirror and ground glass focal plane. Illustrated at left. and below. Voucher No. 12, 28 April 1842, U.S. to William Würdman for "additions to a camera lucida."
Below is my photograph from the "Long Camp" of Frémont's second expedition. The site (N38° 41' 03", W119°: 57' 19") was located in October 1996 and photographed the following February. Like many of Preuss's drawings, it takes in an angular view of about 90°; the eye cannot cover the whole scene at one glance. A camera lens of normal focal length--one that gives a natural perspective--takes in an angle of about 40°. For this photograph, a number of overlapping exposures were made with a 48mm lens on a 35mm camera. A wide-angle lens of 21mm focal length would cover the width of the scene, but the mountains in the background would shrink to nearly nothing. The camera obscura, fitted with a lens providing a normal perspective, would also require taking a number of views, as shown above. The black wiggly line represents the visible horizon from the vantage. Each of the separate views is reversed (by the camera) left to right. 
It is probably flipped over and end for end at this point, but I have left it reversed. Because the next step is to present the drawing to the engraver, and it is in this reversed orientation that the plate for printing is made. The printing made from the plate will be a correct view as intended by the artist. There is another issue to be addressed. All of the plates presented in the printed report were to be in the same 4" by 7" size. In the case of this view of the Long Camp, there is a good deal of horizontal compression to bring the image to this required 4/7 ratio. Many of the scenes show people and animals. This adds scale and interest to the illustrations of the text. It is not known at what point in the production these figures were added. Plates printed in the 1843 edition of Frémont's 1st expedition report were re-engraved for the reprinting of that report in combination with the 2nd expedition report of 1845. There are slight differences in the later engravings, and different placement of people and animals. In some cases the count of figures is also different. It may be that the figures were actually added by the engraver. Since none of the original field sketches, or original Preuss drawings exist today, we have only the work of the engravers.
more on camera obscura and lucida
|
||||||||||||||||||||
In
outfitting his expeditions, three of Frémont's
purchases were for camera lucida and
camera obscura:
Mention
is made of the camera being used by the artist on the Wilkes
expedition of 1838-1842: "Mr. Drayton took a camera lucida
drawing of one of the largest trees, which the opposite
plate is engraved from."
The
individual sketches 1,2,3,4 in the top illustration, are
then assembled in reverse order 4,3,2,1 and overlapped the
amount required to index them. This completed view is still
reversed left-right. The artist traces this and fills in
details.
