Booksellers, and Printers.”  All these heads are illustrated by anecdotes—­some of them well known, others drawn from uncommon sources—­and all replete with useful information, and furnishing an exhaustless store of entertainment.  Such a volume is, indeed, a book for the people, and will do more towards the spread of knowledge, and the excitement of those engaged in its pursuit, than scores of fine-spun theories cramped up with technicalities.  For young people we consider this book a real treasure; since the examples selected are not those of men who became intoxicated with their success, or gave up useful occupation for mere elegant literature or experimental knowledge; but the instances are chiefly of such as have turned their genius to good account, or for the benefit of themselves and their fellow men.  We call such men the honourables of the land, whose examples should be written in letters of gold, and on monuments of marble, as helps to social duties and for the imitation of after times.

We have marked for our next number a few extracts which will be interesting to our readers to explain the mode by which the heads of a chapter are illustrated.  The biographettes of John Hunter, Simpson, J. Stone, and Fergusson, and the introductory illustrations of Newton, are the most striking portions of the volume; and they maybe read and re-read with increasing advantage.  Of Hunter and Fergusson there are good portraits.

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SPIRIT OF DISCOVERY.

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Block Machinery.

Mr. Faraday has lately described at the Royal Institution, Brunel’s Block Machinery at Portsmouth, with a set of magnificent models of this admirable invention, which were lent to the Society by the Navy Board.  They consist of eight separate machines, which work in succession, so as to begin and finish off a two-sheaved block four inches in length.  These were put by Messrs. Maudsley and Field’s men (who made them) into such communication and action, as to perform the set of operations in the most perfect manner.

Mr. F. briefly stated that the Block Machinery of Portsmouth, by adjustments, could manufacture blocks of 100 different sizes—­could with thirty men make 100 per hour; and from the time of its completion in 1804-5 to the present day, had required no repairs from Maudsley, the original manufacturer.  The total cost was given at 46,000 l., and the saving per annum in time of war 25,000 l.  This is a paragon of art which we could see again and again.

Enameled Street Names.

The names of the Streets in Paris have been recently put up on enameled plates; the ground being blue, and the letters white.  The substance on which the enameling is performed is lava in slabs; the same substance has since been used as the basis of certain enameled designs; it is much superior in some points to porcelain in this application, because the necessary exposure to fire does not cause it to crack in the manner that porcelain does.—­From the French.