November 16, 1945
Dr. W.A. Noyes, Jr.
National Defense Research Committee
1530 P Street, NW
Reference: Your No. 10-151, OEMsr-103
13 October, 1945
Dear Dr. Noyes:
Listed below with mention of their respective contributions are the personnel who are employed under Contract OEMsr-103,
and Supplement No. 1 thereto, entitled "Development of an instrument for the rapid determination of particle-size distribution
1. Professor Linus Pauling, Official Investigator throughout the life of the contract, was asked by Dr. J.B. Conant in
a letter dated June 13, 1941, to give his attention to the "old problem of measurement of particle size and particle-size
distribution, .... particularly along the lines of portable instruments which might be developed for the particular purpose
of testing smoke clouds." Professor Pauling relied on June 18, 1941 by proposing the type of instrument which became the subject
of Contract OEMsr-103. The subsequent work followed closely along the path outlined in this original discussion.
2. Professor J.H. Sturdivant was responsible for the supervision of the experimental work and the detailed design of
the instrument throughout the period of the contract.
3. Mr. William N. Lipscomb, Jr., employed from June 7, 1942 to June 30, 1943, contributed greatly to the development
of the instrument. He produced multidisperse, stable smokes for testing the instrument, compared several arrangements for
charging the particles, investigated with the electron microscope the separation of particle sizes by the instrument, and
examined the precipitation process mathematically.
4. Dr. Thor R. Rubin, employed from February 23 to September 30, 1942, studied unidisperse smokes for testing the instrument,
assembled and put into operation the first instrument, and improved the airflow through it to obtain a steady pencil of smoke.
5. Dr. Eugene H.Eyster, employed October 1 to December 31, 1941, searched the literature, uncovered the parallel experiments
of Rohmann, and prepared a vacuum-tube electrometer for use in the instrument.
6. Dr. Austin L. Wahrhaftig, employed December 1, 1941 to February 28, 1942, constructed the power supply for charging
and deflecting the smoke stream.
7. Dr. Charles D. Wagner, employed August 20 to September 20, 1941, assisted in preliminary measurements.
8. Mr. George Standart, employed part time between November, 1942, and May, 1943, assisted Mr. Lipscomb.
The work of Contract OEMsr-103 covered the design and investigation of an instrument in which the particles in a smoke
stream could be charged electrically and precipitated on a collector at positions correlated with the sizes of the particles.
A theoretical analysis showed that the function relating locus of precipitation to particle size is double-valued; the distribution
is turned back upon itself in such a way that the smallest particles precipitate with the largest. The agreement between theory
and experiment is fairly good, but the range of sizes of the particles precipitated at a given point is rather large. It was
concluded that possible the precipitation apparatus could be developed into a usable laboratory instrument, but that it could
hardly be perfected for field use.
I hope that this letter provides the information you desire for the history of Division 10 activities. Please let me
know if further details on OEMsr-103 are needed.