The "Century" is little more than a Catalogue Raisonné, although each matter of invention is as fully and intelligibly stated as was required in the Patent office specifications of the period. To give some idea of its contents, we shall enumerate only the first twenty-five. 1. Seals abundantly significant; 2. private and particular to each owner; 3. a one line cipher; 4. reduced to a point; 5. varied significantly to all the 24 letters; 6. a mute and perfect discourse by colours; 7. to hold the same by night; 8. to level cannon by night; 9. a ship-destroying engine; 10. how to be fastened from aloof and under water; 11. how to prevent both; 12. an unsinkable ship; 13. false destroying decks; 14. multiplied strength in little room; 15. a boat driving against wind and tide; 16. a sea-sailing fort; 17. a pleasant floating garden; 18. an hour-glass fountain; 19. a coach-saving engine; 20. a balance waterwork; 21. a bucket fountain; 22. an ebbing and flowing river; 23. an ebbing and flowing castle clock; 24. a strength increasing spring; and 25. a double drawing engine for weight. We find in the "Century" that three of the articles refer to improved seals and watches; two to games; two to arithmetic and perspective; six to automata, or self-acting mechanical contrivances; no less than twenty-three to ciphers, correspondence, and signals: in short, secret writing and telegraphs; ten to useful appliances in domestic affairs; nine are wholly mechanical; upwards of thirty-two were intended for use in naval and military affairs; and thirteen, including his Water-commanding Engine, were connected with hydraulics. It is singular that he professes "to have _tried and perfected_ all these," words of great import in all matters of novel invention. That age was fond of patronizing what we should now-a-days be disposed to call "nic-nacs." Ingenious automata, curious toys and works of art, small fountains, singing birds, and similar curiosities attracted the serious attention of the virtuosi of the 17th century; so that we need not feel surprised that the Marquis set up a speaking Brazen Head; or that it should be of gigantic proportions, for he was always regardless of cost in such matters, and was never small where he could be great in developing his resources of ingenious contrivance. Wherever it was possible, he was magnificent--fortifications, embankments, ships rowing against wind and tide, great floating baths, and gardens, large cannon, in short, he was princely in his expenditure of his private fortune on whatever he undertook to perform, whether in war or in peace. It was thus he spent, lent, and lost for his King and country £918,000. He particularly notices that he laid out on buildings and experiments at Vauxhall, the sum of £59,000. But these items are far from representing his actual expenditure, although they indicate the scale of his operations; and taken at their value two centuries back such sums manifest marvellous munificence.