MIL-W-46374 is a specification first published on October 30, 1964, for US military watches. The 46374 was specified as an accurate, disposable watch. In its span, it encompassed metal and plastic cased watches with both mechanical and quartz movements. The 46374 replaced the MIL-W-3818, reducing cost and inheriting the dial from the MIL-W-3818B. These were lower quality watches than the 15 jewel movements, the transition started as US involvement in Vietnam ramped up. Revision A was released in 1968. Regarding Revision B from 1976, it "added radiation symbols to the dial, indicating that the luminous markers were radioactive, H3 for tritium. Revision D expanded the scope of the specification to encompass a wider range of watches." Pilots, divers, and other specialties continue to have military watches available for issue.
Dial font
In 1957 the DOD released MIL-C-18012A, a specification detailing the legibility of numerical displays for aircraft dials and readouts, and updated it with MIL-C-18012B in 1964. At the same time as 18012B was released, so was 46374. The font 46374 inherited from W3818B is unique, "It borrows elements from the super legible Futura and Gothic style fonts of the day but it is mostly influenced by the numerical font shown in MIL-C-18012A. Look particularly at the flat-topped "3" and the simple geometric shapes of the other numbers. Although the numbers used on the watches are more rounded and bolder, the only significant departure the watch designers seem to have taken is with the "9" and "6" which have rounded and more curved tails." Uncluttered, legible dial designs like the Waltham A-13, and the Chelsea Army Message Center Clock inspired the US Army’s Frankford Arsenal in Philadelphia who created the dial specifications and designs, and "The minute hand in the Mark I Chelsea seems to have lent a strong influence to the hand designs used in MIL-W-3818B watches."
Quote: "The most significant changes in the new spec were a tightening of the standards for magnetism, vibration, and water resistance and some refinements to the "Dark Viewing" requirement."
Type 1: 15 jewels, plastic case, first 46374 to be maintainable, accuracy +-30 seconds a day
Type 2: usu. 7 jewels, usu. plastic case accuracy +- 60 seconds a day
First 46374 with a Quartz movement, Types 3, 4, 5
Type 3: accuracy.7 secs a day, battery installed
Type 4: As Type 3, battery in box
Type 5: As Type 3, battery not included
Manufactured by Hamilton, Marathon, Stocker and Yale
E
May 31, 1989
Because of high radiation emission from painted tritium luminous, the luminous was replaced with hermetically sealed tritium vials surrounding the outside of the dial, and on the hands
New dial with serif style font
Quote: "In addition to the dial layout changes the "E" revision calls for interchangeability of all parts on Type I watches on the same model from the same maker. The requirement of less than 25 milliCuries of radioactive emission from the watch face was also added to this specification."
