A description of the dipleidoscope, or double-reflecting meridian and altitude instrument : with plain instructions for the method of using it in the correction of time-keepers / by Edward J. Dent.

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A description of the dipleidoscope, or double-reflecting meridian and altitude instrument : with plain instructions for the method of using it in the correction of time-keepers / by Edward J. Dent. Credit: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.. Public Domain Mark