A Special Semicircle, Called Angleometer.--Having but one reflector which serves both as index and horizon glass, this instrument is free from the corrections accompanying the horizon glass of other instruments, can be made without scale yet accurate enough for meridional lunar declination for Greenwich time,
As the ray of light is reflected but once the luminosity for stellar observations is decidedly advantageous, thereby increasing three fold the number of stars that may be used. Approved by the best men, with whom I have consulted.
The special vernier reading to 17o degrees enables observations of heavenly bodies of high altitude, and with the artificial horizon.
There being no parallax, as with other instruments, makes it good for land surveys, as in measurements of near-by objects.
The simplicity of construction and method of making the m icrometer enables the instrument to be sold at a price one-third off the present instruments, and will be a boom to the AmeriCan production of these instruments, now almost wholly made" abroad.
,: This instrument is made to withstand the severest service, and its freedom from the many corrections of other instruments renders it more easily applicable by the average seaman.
A Parallel Rule, that will work with either side down, and that is capable of advancing straight across the chart, whether the rule *Working models submitted ; sketches of various forms accompany this paper.