On August 7, 1869, the first application of the spectroscope to the examination of the corona of the sun was the beginning of the revelation of the inner mysteries of the constitution and activities of the great luminary. The transit of Venus that occurred on December 6, 1882, was fruitful in measurements, by which the estimates of the distance of the sun were reduced from the long-accepted figures, 95 to 92 millions of miles. Yet this loss of three millions of miles resulted from the apparently trifling change of reckoning the sun’s parallax at 8.82″, instead of 8.57″. An occurrence of vast practical advantage to the whole nation was that of November 18, 1883, when the four standard meridians of railroad time were adopted and put into use. From that day the clocks of the Union were set to keep either Eastern, Central, Mountain, or Pacific Coast time. Professor Edward E. Barnard had used the magnificent telescope of thirty-six inches aperture, belonging to the Lick Observatory in California, but a short time before he astonished the world by discovering a fifth satellite of Jupiter, although it appeared as but a faint speck of light. Besides other honors for this achievement, in 1894 the French Academy of Sciences awarded him the Arago medal, of the value of a thousand francs, a distinction given but twice before, first to Le Verrier, for the discovery of Neptune in 1846, and to Asaph Hall, for finding the two moons of Mars in 1877. “Personal equation” is the name given to the amount of error to which any person is habitually liable in attempting to note the time of a fixed occurrence. When the astronomer looks at a star passing the cross-wires of his transit, he is likely to make the record one or two tenths of a second after the true time, or possibly a like small amount of time before the actual occurrence, by anticipation. This is not a matter of wrong intention, nor due to willfulness. But in precise observations, especially where comparisons are to be made between the records of several persons, the “personal equation” must be determined, if possible, and allowed for. Various methods of correcting this inaccuracy have been used. But the best is that of Frank H. Bigelow, of the Nautical Almanac Office, Washington, who, in 1890, devised a process of taking star transits by photography. It entirely does away with this source of error, and has proved of great value. XV. DISCARDED DOCTRINES AND ABANDONED IDEAS. A few generations ago an eight-day clock was to be found only in the homes of well-to-do people, and a gold watch was a symbol of wealth, such as to subject its wearer to a special tax. In this age of dollar clocks and Waterbury watches, almanacs are no longer indispensable. We do not regulate our time-pieces by the rising and setting of the sun; nor can a future Jay Gould lay the foundation of his fortune, as did the one best known by that name, by setting up rural noon-marks for a fixed fee.