352 



GREEK SCIENCE. 



opinions of their masters, maintained a different doctrine, and invented 

 many absurd hypotheses to account for the operations of the various 

 machines above alluded to. 



Mirrors. 



Hebrew 

 mirrors. 



V. OPTICS. 



It would be more easy to become the encomiast of this science than 

 to trace its history ; for there is no department of philosophy more 

 deserving of our study, whether we consider its beauty or the multi- 

 plicity of its phenomena. Air, which serves as the medium of speech, 

 and the vehicle of sound, enables us to carry on an intellectual inter- 

 course with our fellow- creatures ; but how considerably is that inter- 

 course improved and facilitated by light, which brings before us their 

 image their image which tells us so much of their character and of 

 their thoughts! The eye, so susceptible of multifarious impressions, 

 conveys to the mind ideas of the forms by which bodies are limited, 

 the colours by which they are adorned, their relative positions, and 

 their motions. By a single look this admirable organ enables us to 

 seize the indefinite modifications of the numerous objects that diversify 

 our richest landscapes ; and when it becomes aided by the instruments 

 furnished by our knowledge of the laws of reflection and refraction, it 

 contemplates the two kinds of infinity that would otherwise have re- 

 mained unknown that of animalcule and of small inanimate objects, 

 imperceptible by reason of their minuteness and that of the celestial 

 bodies, invisible by reason of their remoteness ; thus opening to natural 

 history a new field, to astronomy a new heaven, and inviting us suc- 

 cessfully to contemplate the universe of the poet : 



" Without bound, 



Without dimension, where length, breadth, and height, 



And time and place are lost." 



But our present employment must not be that of eulogy. 



The ancients for several centuries seem, as was naturally to be ex- 

 pected, to have had no knowledge of the theory of optics, and to have 

 made no advances of consequence in the construction of optical instru- 

 ments. The observance of a straight rod, partially immersed in water, 

 would suggest to them the idea of refraction ; and the sight of their 

 own image, reflected from the smooth surface of a quiescent liquid, 

 would naturally lead them to attempt the construction of artificial 

 mirrors. Accordingly, we find mention not merely of mirrors, but of 

 metallic mirrors, in the earliest writings now extant, those of Moses. 

 In Exodus xxxviii. 8, though Luther, and some few after him, trans- 

 late the passage " He made the hand-bason of brass, and its stand also 

 of brass, in the presence of the women who served before the door of 

 the tabernacle;" yet they have been censured for this, since the Sep- 

 tuagint, the Vulgate, the English, and the Dutch Bibles, agree in 

 translating ' Beramoth' " of the mirrors," made, say many of the com- 

 mentators, of polished brass. In the book of Job, too, now generally 



