Perhaps no class of men have deserved more of their country and of mankind than the great inventors and discoverers in astronomy, chemistry, engineering and other departments of science; yet very little is known of many of them in proportion to the acknowledged good which has resulted from their labours. We possess works of art commemorating the achievements of heroes in the field, and of statesmen in parliament, but until now no work of any magnitude has ever been executed in honour of men whose doings have laid the foundation of our commercial prosperity. We are, however, able to state that this can no longer be said, as Mr. Walker, of 64, Margaret-street, Cavendish-square, has, after an extended period of labour, produced an engraving which must remain an enduring record of our greatest era in science--the early part of the present century. At that epoch of time, steam, under the hands of Watt, Symington, and Trevithick, was commencing its marvellous career; astronomy and chemistry began to reveal their long-hidden secrets; while the discovery of vaccination, by Jenner, had already rescued thousands from death to enjoy the blessings left as a legacy by many a silent worker in science.... We may fairly state that we have never seen so large a body of men arranged in a group, where it is necessary that all should, in a measure, present their faces turned towards the spectator, so free from that stiffness which is the general fault of works of this class. For this, great praise is due to John Gilbert, by whom the original picture (drawn by J. F. Skill and W. Walker) was designed. The engraving has been executed by W. Walker and George Zobel; while in order to render the work complete, a series of memoirs have been drawn up by Mr. W. Walker, Jun., and furnished with a short introduction by Mr. Robert Hunt, F.R.S., keeper of the Mining Records. We can only now say of the book, that while many of the memoirs are necessarily brief, one, that of Trevithick, contains the most information yet published regarding that eminent engineer. BUILDING NEWS.