One of the most striking city scenes in the world is the view of London as you approach London Bridge in one of the small, low-decked steamers which ply upon the Thames. London stands where navigation for sea-going vessels ceases on this famous stream, which is crossed at London, within a stretch of three or four miles, by about fifteen bridges, of which seven or eight can be seen at one view under the middle arch of London Bridge. Over all these bridges there is a ceaseless tide of human life, and in the river below, besides long lines of ships at anchor and unloading, there are as many steam-vessels, barges, skiffs, and wherries as can find safe passage. A scene more animated, picturesque, and grand is nowhere else presented, especially when the great black dome of St. Paul's is visible, hanging over it, appearing to be suspended in the foggy atmosphere like a black balloon, the cathedral itself being invisible. Three of these bridges were built by the engineers, father and son, whose name appears at the head of this article, and those three are among the most wonderful structures of their kind. One of these is London Bridge; another is called Southwark, and the third, Waterloo. The time may come when the man who builds bridges will be as celebrated as the man who batters them down with cannon; but, at present, for one person who knows the name of Sir John Rennie there are a thousand who are familiar with Wellington and Waterloo. He had, however, a pedigree longer than that of some lords. His father was a very great engineer before him, and that father acquired his training in practical mechanics under a Scotch firm of machinists and mill-wrights which dates back to the reign of Charles the Second. It is to be particularly noted that both John Rennie, the elder, and Sir John, his son, derived an important part of their education in the workshop and model-room. Both of them, indeed, had an ideal education; for they enjoyed the best theoretical instruction which their age and country could furnish, and the best practical training also. Theory and practice went hand in hand. While the intellect was nourished, the body was developed, the hand acquired skill, and the eyesight, certainty. It is impossible to imagine a better education for a young man than for him to receive instruction at Edinburgh University under the illustrious Professor Black, and afterwards a training in practical mechanics under Andrew Meikle, one of the best mechanics then living. This was the fortunate lot of Rennie's father, who wisely determined that his son should have the same advantage.