This section includes both black and white and color negatives, as well as transparencies and some coded prints. They are in steel card file drawers, arranged by the code numbers assigned to them by Otis Marston. (There are other coded negatives, slides, and prints in other locations, where they are filed by date, location, subject, or photographer rather than by code.)
Marston code
The Marston code consists of three general elements: numbers representing the date of the photo; letters serving as an abbreviation for the subject; numbers representing any of a number of distinguishing characteristics. For example, 515 MECN 39.2 means a negative taken in May 1951 in Marble Canyon at milepost 39, the second exposure taken that day at that spot. Coded negatives are filed in strict chronological order by year, then month, and finally day. When these are identical, they are filed by letter subject code in strict alphabetical order. When these are identical, too, they are filed by the third element in the code (see below).
In the first element of the code, the first two digits represent the year. For example, 70 indicates either 1870 or 1970, while 09, could mean either 1809 or 1909. The same years from different centuries (eg., 1870 and 1970) have been interfiled indiscriminately. Multiple years are filed after the last envelope of the first year. For example, 46-50 would follow 4612, or December 1946. As in this last example, the first two digits may be followed by others expressing the month and day. In this way, 586 would mean June 1958 (or 1858), 70-9-30 is September 30, 1970, and 09121 is either December 1 or January 21, 1909. The filing sequence is: 70, 70-1, 70-1-1, 70-1-2, 70-2, 70-2-1, 70-2-28, 70-3..., 70-12-31, 70-71, 71.
The second element of the code consists of four letters, usually representing the first and last letters of the name of the subject or place. For example, Grand Canyon is GDCN and Norman Nevills is NNNS. Where there are more than one person as the subject, the letters may be split between the initials of the various persons. Thus, a photo of Masland and Marston might be MDMN, while one of Masland, Marston, Atherton, and Desloge might be MMAD. Occasionally there is a lack of consistency in the abbreviations: John Wesley Powell is both JNPL and JWPL; the steamer Cochan is both SRCN and CNSR.
The third element, comprising a varying number of digits, can represent any one of several things, or, more often, a combination. In river scenes, the first of these numbers may stand for the milepost along the river depicted. For example, 566 MECN 48 is a photo taken June 1956 in Marble Canyon at mile 48. Alternatively, the number may be that of a negative or slide in a series of pictures of the same subject. Thus, 486 DKMN 3 is the third in a series of photos taken of Dock Marston in June 1948. Such series numbers are also commonly added after a milepost number when several photos were taken at the same spot; 566 MECN 48-3 indicates the third exposure taken there that day at mile 48. In this case, a dash or decimal point is used to separate the two numbers. Both should be read, and filed, as dashes (even though on occasion Marston himself filed the decimal points as decimals). Thus, the sequence would be 46.1, 46.2, 46.9, 46.10, 46.11, 46.99, 46.100 whether a dash or a decimal point were used. There may be a third number, representing perhaps a file number of a photo by a famous photographer or the frame number on a roll of 35mm film. Occasionally, a final number will indicate the existence of more than one frame on a strip of 35 mm film. For example, 615 CORR 16-1-4 might mean roll 16, frames 1 through 4. More often, when there are more than one frame in an envelope, as is commonly the case with 35mm negatives, each frame will be assigned its own slightly variant number, with all three or four code numbers listed on the same envelope (eg., 615 CORR 15-9 and 615 CORR 16-10). Since there are seldom cross references, this means one must look around a bit. I have filed these by the lowest number on the envelope, so one need only look up to the desired number. The 615 CORRs in the above example would be filed as 615 CORR 15-9.