[ RadSafe ] Bubble Sextant

[Gaglierd, Tony]

While cleaning out the former residence of a gentleman who was a chemist on
the Manhattan Project a relative using Geiger counters that the gentleman
had, found elevated radiation levels in the basement. I responded to the
call and found two Bubble Sextants manufactured by Bendix Corp.

"AIRCRAFT OCTANT / MARK IV / BUR. OF AERO. U.S. NAVY / SER. NO. 989-41 /
ORDER NO. 83600 / F.S.S.C. NO. 88-0-250 / MFRD. UNDER PATENTS NOS / 1556994
1674500 1970543 / 2221152 / OTHER PATENTS PENDING / PIONEER INSTRUMENT /
DIVISION OF BENDIX AVIATION CORPORATION / BENDIX, NEW JERSEY, U.S.A."

I also found Two Bubble Sextants manufactured by Bausch & Lomb. 

"U.S. ARMY AIR CORPS AIRCRAFT OCTANT / TYPE NO. A-8 SERIAL NO. A.C.40-10 /
SPECIFICATION NO. 27914 / ORDER NO. AC-144464 / MFR'S ASS'Y DWG. NO. 277728
/ BAUSCH & LOMB OPTICAL CO. / ROCHESTER, N.Y. U.S.A." and "U.S. PATS.
1,531,615; 1,674,550; 1,703,705; 2,080,851"

>From the Smithsonian Museum of natural history web site:
http://americanhistory.si.edu/collections/navigation/object.cfm?recordnumber
=451519

I found the following information:

The Mark IV bubble sextant has a mechanism designed by Lt. Comdr. Ira Hobbs
of the Naval Aircraft Factory that averaged observations along with the
times at which they were made. It also has a novel method of illuminating
the bubble designed by Gregory Rylsky, an engineer employed by Pioneer. The
form was introduced in 1941 and remained in use throughout the war.
 
Bausch & Lomb made this instrument for the U.S. Army shortly before America
entered World War II. It is based on the Bureau of Standards design, but
with an improved method for illuminating the bubble and the marking pad
designed by George Gallasch and Henry Kurtz, both of Bausch & Lomb. It also
has a mechanical averager that can handle eight consecutive readings. Thomas
L. (Tommy) Thurlow of the Army Air Corps filed a patent application for an
averager on August 3, 1937, but was scooped, by one day, by P. F. Everitt of
Henry Hughes & Son, the leading British manufacturer of nautical and
aeronautical instruments. 

Gregory Rylsky's patent is for a system of eluminating the bubble using an
incandescent light bulb.

All of these devices were radioactive and upon Gamma Spectroscopic analysis
indicated the presence of Radium 226 in amounts of 1 - 2 uCi. 

The activity appeared concentrated in the viewing area or the lens holder in
the Bausch and Lomb Instrument.

I suspect the radium was used to activate some fluorescent materials to
produce light to view the bubble at night.

Any one knows what the radium was used for?

Thanks

Tony Gaglierd
Radiological Officer
Allegheny County Health Department
301 39ths Street
Pittsburgh, PA 15201
412-578-7970