US Patent: 455,644
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| Micrometer Calipers
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Patentee:
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| John D. Sloane (exact or similar names) - St. Paul, MN |
| Manufacturer: |
| Not known to have been produced |
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Patent Dates:
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| Applied: |
Jan. 03, 1891 |
| Granted: |
Jul. 07, 1891 |
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Joel Havens
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Description: |
| My invention relates to improvements in that type of micrometer-calipers designed especially for use in steam-boiler inspection to o measure the thickness of the boilerplates. In order to determine the deterioration and erosion of the plates of boilers after long use, it is necessary and generally required bylaw to drill through the boiler plate a hole of sufficient diameter to admit the calipers or other measuring instrument. For calipers of the ordinary type it is necessary to drill a large hole through the plate, usually at least an inch in diameter, which is afterward closed by a screw-plug, but which nevertheless seriously weakens and injures the boiler. The object of my invention is to provide an. instrument by means of which the examination of the boiler may be accurately accomplished without this injury to it. In using my improved calipers it is unnecessary to drill a large hole through the plate, as it can be inserted through one from one-eighth to one-quarter of an inch in diameter, which, when properly plugged, causes no appreciable injury to the boiler. My invention consists in providing a pair of calipers one leg of which is a small barrel or cylinder, the other leg consisting of a small rod sliding within the barrel, each provided with a caliper-point off set from in their common axis. The inner leg, while held by means of a feather normally in position with the caliper-points in line with each other, may be pushed outward to free the feather from its groove and turned in the barrel, so as to swing its point away from the other or fixed point to permit of its being inserted through the opening in the plate, after which it is turned back into position for measuring. My invention also consists in improved means for setting the calipers when the measurement is taken, or so recording the measurement that the instrument, may be removed from the plate and the reading taken afterward.
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