Belfort Instruments 800A Microbarograph
This is a Belfort Instruments Model 5-800A microbarograph. It was made for the US Government and bears the military designation ML-563A/UM. I'm not sure of the date of manufacture but the design dates from at least the 1960s. It has a spring-driven 7 day clock drive and works very well. I use a 1071-M chart (available from Belfort Instruments) which ranges from 965 to 1050 mb. One of the last modern microbarograph designs, a very sensitive instrument.
From 1961, US Patent 2,997,879 by Belfort of the design for this microbarograph is available below (5 pages):
A 1977 sales brochure for the 800A microbarograph may be downloaded here (2 pages):
