MECHANICS AND USEFUL AETS. 69 



and the clabber is always renewed from the painted paper till the 

 color is exhausted, when the paper is again replenished from the re- 

 serve in the corner. 



As the color on the paper becomes less and less in quantity, 

 smoother leaves may be employed ; and when the paper seems to be 

 almost wholly without paint, the smoothest leaves will prove suc- 

 cessful, for these require extremely little color. Should the natural 

 color of the leaf be desired, it can be got by using paint of the color 

 required ; but, in many cases, purely artificial tints produce the most 

 pleasing and artistic results ; thus, burnt sienna gives a very pleasing 

 red tint ; and of all colors this will be found to work with the greatest 

 ease. 



By the process now described, the most beautiful results can be 

 gained ; but the effect will be better if, when the impression is being 

 rubbed off, the leaf, together with the paper in which it is enclosed, 

 is placed on something soft, as half a quire of blotting paper. Should 

 the first attempt not prove very satisfactory, a little experience will 

 be found to be all that is required ; and now the most common leaf 

 will be seen to have a form of the most lovely character. 



Collections of leaves of forest-trees will prove of the deepest inter- 

 est, or of all the species which we have of any kind of plant ; thus, if 

 the leaves of the black, red, American, and golden currant be printed 

 together with that of the gooseberry, all of which belong to one bo- 

 tanical genus or group, the variation or modification of the form will 

 be seen to be of the deepest interest. 



IMPROVEMENTS IN THE SCIENCE OF WAR. 



The existence of civil war in the United States, and the efforts for 

 a more complete armament on the part of the European powers, have 

 directed the current of invention during the past year very strongly 

 towards the effecting of improvements in warlike implements and pre- 

 parations, and it is probable that more inventions pertaining to the 

 science of war have been brought out during the past twelve months 

 than during any equal former period of the earth's history. From a 

 multiplicity of facts and suggestions, we present our readers with a 

 resume of such points as have seemed to us most important and inter- 



esting. 



IKON-CLAD SHIPS. 



The engineering energy of the foremost European nations seems 

 now to be mainly directed to the building of iron-cased vessels of the 

 Gloire and Warrior type. France has now no less than fifteen of 

 these tremendous engines of war; England has four ; while Russia 

 has recently contracted with English companies for six. At the out- 

 set, the idea of any iron-cased vessels, whether for steam-ranis or frig- 

 ates, found no favor with the English admiralty, and it was not till 

 the results of French experiments as to the resistance which they 

 offered to shot became known in England, with the additional fact 



