text:  On visiting the Polytechnic Institution--"which means I understand a place in which specimens of every science and art are to be seen in some mode or other there being no science or art of any other country unknown here"--he briefly enumerates the oxyhydrogen microscope "by which water was shown so full of little animals nay even monsters as to make one shudder at the thought of swallowing a drop"--the orrery the daguerreotype and the diving-bell (in which he had the courage to descend ) as the objects principally deserving notice "since it would require several months if not years to give that attention to each specimen of human industry which it demands in order thoroughly to understand it