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The plate level is then used, rotating it 90 degrees between readings to level the instrument more precisely. The Fell All-Way precision level, one of the first successful American made bull's eye levels for machine tool use, was invented by William B. Fell, Rockford, Illinois prior to World War II in 1939. [1]
An integrating-averaging Cirrus Research's Optimus sound level meter which complies with IEC 61672-1:2002. A sound level meter (also called sound pressure level meter (SPL)) is used for acoustic measurements. It is commonly a hand-held instrument with a microphone.
The Fell All-Way precision level, one of the first successful American made bull's eye levels for machine tool use, was invented by William B. Fell of Rockford, Illinois in 1939. [2] The device was unique in that it could be placed on a machine bed and show tilt on the x-y axes simultaneously, eliminating the need to rotate the level 90 degrees.
Luxury Is Calling. One man’s trash is very often another man’s treasure on eBay, which has been selling head-scratching items since 1995. But eBay is a place for a lot more than just cheap ...
The Y level or wye level is the oldest and bulkiest of the older style optical instruments. A low-powered telescope is placed in a pair of clamp mounts, and the instrument then leveled using a spirit level, which is mounted parallel to the main telescope. The term dumpy level (also builder's level) endures despite the evolution in design. They ...
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In 1914 and 1915, the Forestry Quarterly published a series of articles on the use of the Abney level. [6] [7] [8] These tutorial articles remain useful today, but the primary reference for usage is the 1927 Abney Level Handbook. [3] The Abney level is typically used at the eye height of the surveyor, either hand-held or mounted on a staff at ...