_Attractions of Telescopic Work._—In concluding our comments we may briefly refer to the importance and pleasure attached to telescopic work, and the growing popularity of observation in the attractive and diverse field of astronomy. A telescope may either be employed as an instrument of scientific discovery and critical work, or it may be made a source of recreation and instruction. By its means the powers of the eye are so far assisted and expanded that we are enabled to form a clearer conception of the wonderful works of the Creator than could be obtained in any other way. Objects which appear to natural vision in dim and uncertain characters are resolved, even in telescopes of the smallest pretentions, into pictures of well-defined outlines containing details of configuration far exceeding what are expected. And it is entirely owing to the exact measurements obtained under telescopic power that many of the most important problems of astronomy have been satisfactorily solved. To this instrument we are indebted, not only in a great measure for our knowledge of the physical features of many celestial bodies, but also for the accurate information we have gained as to their motions, distances, and magnitudes. Apart from this it is capable of affording ample entertainment to all those who are desirous of viewing for themselves some of the absorbing wonders of astronomy as described in our handbooks. And a demonstration of this practical kind is more effective than any amount of description in bringing home to the comprehension of the uninitiated the unique and picturesque side of astronomy. CHAPTER V. _THE SUN._ Solar Observations.—Early notices of Spots.—Difficulties of the old observers.—Small instruments useful.—Tinted glass.—Solar Diagonal.—Structure of a Spot.—Methods of Drawing.—Ascertaining Dimensions.—Observer’s aims.—Eclipses of the Sun.—Periodicity of Spots.—Crateriform structure.—“Willow-Leaves.”—Rotation of the Sun.—Planetary bodies in transit.—Proper motion of Sun-spots.—Rise and decay of Spots.—Black Nuclei in the umbræ.—Bright objects near the Sun.—Cyclonic action.—Sudden outbursts of Faculæ.—Shadows cast by Faculæ.—Veiled Spots.—Recurrent disturbances.—Recurrent forms.—Exceptional position of Spots.—The Solar prominences. “Along the skies the Sun obliquely rolls, Forsakes, by turns, and visits both the poles; Diff’rent his track, but constant his career, Divides the times, and measures out the year.” The Sun is not an object comprehended in the title of this volume. But to have omitted reference to a body of such vast importance, and one displaying so many interesting features to the telescopic observer, would have been inexcusable. We may regard the Sun as the dominant power, the controlling orb, and the great central luminary of our system. The phenomena visibly displayed on his surface assume a particular significance, as affecting a body occupying so high a place in the celestial mechanism.