I have a large collection of old catalogs, magazines, service manuals, journals, brochures, and other paper items related to my historical interest in precise Time & Frequency. Occasionally I scan them so others can enjoy them too.
HP 8504A -- a detailed description of the Vector Voltmeter (Hewlett Packard Journal).
100 leap milliseconds -- an example of a pre-UTC time step.
Time Scales (5 pages) -- the original 1968 Metrologia article where Louis Essen documents the difficulties coordinating astronomical time and atomic time. Contains an early reference to "leap second" which he calls "moving the minute marker along by 1 second on a prearranged date, possibly 1 January and 1 June". Article also includes references to 50 ms (a leap shilling? ;-) and 100 ms time steps.
Frequency of Cesium in terms of Ephemeris Time (2 pages) -- the original 1958 Phys Rev article where, after 3 years of measurements, Markowitz & Hall of USNO (the guys with the telescope) and Essen & Parry of NPL (the guys with the cesium clock) find out that one second is 9 192 631 770 ± 20 periods of the hyperfine transition of cesium. As far as I know was the only time this was every measured. After that the SI second was defined from 9192631770 Hz and the switch flipped from astronomical time to atomic time.
Atomic Second -- In 1965 the Twelfth General Conference of Weights and Measures is not quite ready to officially define the second in terms of Cesium.
The Atomic Hydrogen Maser (9 pages) -- 1965 Metrologia article where Norman Ramsey describes the theory and performance of his Hydrogen Maser (looks like a H-10 prototype).
Cesium Beam Atomic Time and Frequency Standards (18 pages) -- 1965 Metrologia article where the accuracy and uncertainty of an early NBS (now NIST) cesium beam frequency standard is evaluated.
Accuracy Evaluation of the primary frequency standard NIST-7 (32 pages) -- by contrast, the 2001 Metrologia article describing the theory, accuracy and uncertainty of the best and last NIST cesium beam frequency standard.
Initial Results of the NAVSTAR GPS NTS-2 Satellite (23 pages) -- 1978 PTTI article describing the precise timing of the NTS-2 satellite. This was a precursor of Navstar GPS. This is the earliest reference I've found to the relativistic corrections needed for GPS.
General Relativity in the Global Positioning System -- by Neil Ashby, University of Colorado. This is usually found on the web at a URL called node9.html but here is a properly scanned version. The relativity data he quotes is from the above NTS-2 article. The NTS-2 article is also appended. See Figure 27.
Initial Results of the NAVSTAR GPS NTS-2 Satellite -- a HTML version of one chapter of the article by James A Buisson, Roger L. Easton, Thomas B. McCaskill, U.S. Naval Research Laboratory (NRL).
If you are a retiring Time & Frequency professional please don't throw away any of your old junk when you clean out your office. The older the better; I'd be happy to sort through your boxes and extract old catalogs, magazines, manuals, brochures, journals, and books. One man's junk is another man's goldmine. I'll take anything in print related to precise time & frequency; from pendulums to masers.