MATHEMATICAL SCfEXCES. 8 9 



~\ 



extract from the devices of sorcerers and magicians whatever experimental 

 science could discover therein. In a word, Magistcr Petrus deserved the 

 surname which his pupil gave him of J/.v///.sV/r EsjMviineiiforum. 



Such a guide was invaluable to Roger Bacon in the wonderful inventions 

 attributed to him, for in most of his researches and experiments he was 

 doubtless assisted by the advice of Magister Petrus. His works, more 

 particularly his " Opus Maju.-s," show to what a height he elevated science, 

 substituting the experimental for the scientific method. It is easy to under- 

 stand how the invention of gunpowder, telescopes, magnifying glasses, &c., 

 came to be attributed to him. He merely put into execution, as it would 

 appear, the scientific discoveries of his master, who had observed the 

 phenomenon of refraction and the properties of the loadstone, and who con- 

 structed a movable sphere which reproduced all the motions of the stars. 

 Roger Bacon also devoted his attention to philosophy, and as early as the year 

 1269 he proposed the reform of the calendar (Figs. 62 67). 



But the attitude which he had assumed, and the severity of his criticisms 

 upon the most illustrious of his contemporaries, made him many bitter 

 enemies. 



1 1 is principal adversaries or rather, perhaps, his rivals were, like himself, 

 monks of the Franciscan Order. He was denounced to his superiors as being 

 guilty of heresy in his teaching of science, and he was confined in a prison 

 where he could not have any communication with his pupils. The latter, 

 most of whom belonged to the same religious order, and all of whom were 

 famous astronomers or mathematicians, such as Thomas Bungey, Jean de 

 Paris, John Bacon or Baconthorp, nicknamed the Prince of Averroists, 

 did not venture to espouse his cause for fear of being involved in his disgrace. 

 He had, however, a friend in Clement IV., to whom he had dedicated his 

 " Opus Majus," and was, by his order, set at liberty. But, at the death of that 

 pontiff, he was again imprisoned and treated with still greater severity, for 

 he was refused the use of writing materials. He managed, however, to revise 

 and perfect his "Opus Majus," which contains the substance of his doctrine, 

 and he wrote two epitomes of it, far more advanced than the original, with 

 the titles of " Opus Minus " and " Opus Tertium." Both of these books, though 

 they long remained unpublished, were not destroyed, notwithstanding the 

 persecution to which their author was subjected during his lifetime, but it is 

 not many years since they first saw the light. This man of genius, who 



N 



