68 



HISTORY OF SCIENCE. 



place them with respect to our eyes and the objects, that the rays shall 

 be bent and turned in any direction we desire, and under whatever 

 angle we please, and so that we shall see an object either at a distance 

 or close at hand ; and thus we may from an incredible distance read 

 the smallest letters and count the grains of sand, etc. Thus, a boy 

 may appear a giant, and a man seem a mountain, and a small army 



FIG. 25. ROGER BACON'S HOUSE AT OXFORD. 



appear very great. So too may we make the sun and the moon ap- 

 parently descend to this lower world, and show themselves upon the 

 heads of our enemies." 



Besides the "Opus Majtts" there exist other writings of Roger Bacon, 

 such as the " Opus Minus" the '' Opiis Tertium" and a treatise on the 

 Calendar, containing astronomical tables. This 'last work gives proof 

 that Bacon was aware of the error which had accumulated in the Julian 

 Calendar in his time ; and he even proposed the same means of recti- 

 fying it which were applied under Gregory. For all this, Roger Bacon 

 was a believer in astrology, at least, so far as to attribute to the con- 

 figuration of the stars an influence on the temperaments of men, and 



