714 COSMOS, 



The use of the telescope now excited astronomers to the 

 earnest observation of a class of phenomena, some of which 

 could not even escape the naked eye. Simon Marius des- 

 cribed in 1612 the nebula in Andromeda, and Huygens in 

 1656, drew the figure of that in the stars of the sword of Orion. 

 Both nebula3 might serve as types of a more or less advanced 

 condensation of nebulous cosmical matter. Marius, when he 

 compared the nebula in Andromeda, to " a wax-taper seen 

 through a semi-transparent medium," indicated very forcibly 

 the difference between nebulsB generally and the stellar masses 

 and groups in the Pleiades and in Cancer, examined by 

 Galileo. As early as the sixteenth century Spanish and Por- 

 tuguese sea-farers, without the aid of telescopic vision, had 

 noticed with admiration the two Magallenic clouds of light, 

 revolving round the south-pole, of which one, as we have ob- 

 served, was known as " the white spot," or " white ox," of 

 the Persian astronomer, Abdurrahman Sufi, who lived in the 

 middle of the tenth century. Galileo in the nuncius Siderius 

 uses the terms, " stellce nebulosce" and " nebulosce" to desig- 

 nate clusters of stars, which, as he expresses it, like areolce 

 sparsim per athera subfulgent. As he did not bestow any 

 especial attention on the nebula in Andromeda, which although 

 visible to the naked eye, had not hitherto revealed any star 

 under the highest magnifying powers, he regarded all nebu- 

 lous appearances, all his nebulosce, and the milky way itself, 

 as luminous masses formed of closely-compressed stars. He 

 did not distinguish between the nebula and star, as Huygens 

 did in the case of the nebulous spot of Orion. These are the 

 feeble beginnings of the great works on Nebula, which have 

 so honourably occupied the first astronomers of our own time, 

 in both hemispheres. 



Although the seventeenth century owes its principal splen- 

 dour at its beginning to the sudden enlargment afforded to the 

 knowledge of the heavens, imparted by the labours of Galileo 

 and Kepler, and at its close to the advance in mathematical 

 science, due to Newton and Leibnitz, yet the greater number 

 of the physical problems, which occupy us in the present day, 

 likewise experienced beneficial consideration in the same cen- 

 tury. In order not to depart from the character peculiarly 

 appropriate to a history of the contemplation of the universe, 

 I limit myself to a mere enumeration of the works which have 



