Elements of astronomy ..with explanatory notes, and questions for examination . d LPT. Con-sequently in the triangle MPT we have the side PP1, and all the angles tofind the other two sides MP and MP1. Now taking the triangle MPC wehave the side MP (just found) CP a radius of the earth, and the angle MPC the supplement of the moons zenith distance, to find the other partsone of which namely CMP is the parallax. In this manner the parallaxof Mars, was obtained by Lacaille and Wargentin, the former being sta-tioned at the Cape of Good Hope, the latter at Stockholm. If the parallaxat any altitude
Elements of astronomy ..with explanatory notes, and questions for examination . d LPT. Con-sequently in the triangle MPT we have the side PP1, and all the angles tofind the other two sides MP and MP1. Now taking the triangle MPC wehave the side MP (just found) CP a radius of the earth, and the angle MPC the supplement of the moons zenith distance, to find the other partsone of which namely CMP is the parallax. In this manner the parallaxof Mars, was obtained by Lacaille and Wargentin, the former being sta-tioned at the Cape of Good Hope, the latter at Stockholm. If the parallaxat any altitude is obtained, the horizontal parallax can be derived from it;the parallax varying as the sine of the zenith distances. For instance, thesine of MPZ : the parallax CMP : : the sine of ninety degrees : the zenithdistance of the moon on the horizon, i. e. her horizontal parallax. TRANSIT INSTRUMENT. 67 aid of an accurate clock, and a peculiar kind of telescopecalled a transit instrument Fig. 25; within this instru-ment is placed a system of wires like those shown at ac, FIG. TRANSIT INSTRUMENT. Fig. 26, one horizontal and five vertical: the latter beingparallel to each other, and separated by equal intervals;1 FIG. 26.
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