It forms a necessary part of popular lectures that they should possess breadth with brevity, and interest without too great profundity. It is possible to see a large extent of country from a lofty tower without being cognizant of every blade of grass, the perfume of blossoms, or the notes of the sweetest songsters of the groves. In like manner the popular lecturer has to present only so much to the eye of the mind as will give the prominent features of his theme, omitting those details over which the scholar, or the true lover of his subject, dwells with the affection of a fond parent over a darling child. We must look with astonishment at a man of noble birth, who in a period of civil commotion, with a monarch for his friend, and a court at his command, secluded himself during his youth in a stately ancient tower, engaged in abstruse studies and wonderful mechanical operations; and who, late in life, amidst the terrors of civil war was found turning his inventive faculties, like another Archimedes, to the construction of means of defence, and terrible weapons of offence. But it is only those who become immersed in studies, whether of theology, philosophy, or kindred mental pursuits, who can appreciate the growing appetite for what appears to unlettered men as the driest of all dry occupations. The mere pleasure-seeker knows not how much is lost, and how little is gained by sharing the most brilliant gaieties of fashionable life. Look at the ancient astrologers, whose pursuits were once as pure and noble as those of modern astronomers. Amidst wild theories, superstitious beliefs, empirical systems, and pagan divination, a rupture became inevitable: one side adopted stellary divination or Astrology, the other Astronomy, or the simple and true study of the stars. Whatever a man's intellectual pursuits may be, he has the advantage over the mere man of fashion of being engaged in employments which the longest life cannot exhaust. But intellectual pursuits partake either of the negative or the positive; they are useful or useless, and when useless they fritter away and render nugatory the talent that might have been better employed. The Marquis of Worcester affords an eminent example of genius of a high order, grandly and effectively directed towards the advancement of man's political and social position. His contemporary, Dr. John Dee, the Astrologer, together with his friend Kelly, the Alchemist, may be appropriately distinguished as representing a class chimerically inclined, and hurtful to the well-being of society; while a less eminent and less blameable section of chimerical labourers are those of whom the worst we can say is, that they waste much valuable time, energy, and fortune, through attaching themselves to mathematics, mechanics, and other learned pursuits, only in search of marvellous, instead of useful applications.