Prior to the introduction of this method, 8 or 9 lbs. had been the limit of weight for a block.  This process has been perfected at the Stowmarket factory, where blocks varying from the armour-piercing shell charge of a few ounces up to blocks of compressed gun-cotton mechanically true, weighing 4 to 5 cwts. for torpedoes or submarine mines, are now produced.  At the same time the new process ensures a uniform density throughout the block, and permits of any required density, from 1.4 downwards, being attained; it is also possible exactly to regulate the percentage of moisture, and to ensure its uniform distribution.  The maximum percentage of moisture depends, of course, upon the density.  By the methods of compression gun-cotton blocks hitherto employed, blocks of a greater thickness than 2 inches, or of a greater weight than 9 lbs., could not be made, but with the new process blocks of any shape, size, thickness, or weight that is likely to be required can be made readily and safely.  The advantages which are claimed for the process may be enumerated as follows:—­(1.) There is no space wasted, as in the case with built-up charges, through slightly imperfect contact between the individual blocks, and thus either a heavier charge—­i.e., about 15 per cent. more gun-cotton—­can be got into the same space, or less space will be occupied by a charge of a given weight. (2.) The metallic cases for solid charges may be much lighter than for those built-up, since with the former their function is merely to prevent the loss of moisture from wet gun-cotton, or to prevent the absorption of moisture by dry gun-cotton.  They can thus be made lighter, as the solid charge inside will prevent deformation during transport.  With built-up charges the case must be strong enough to prevent damage, either to itself or to the charge it contains.  For many uses a metal case, however light, may be discarded, and one of a thin waterproof material substituted. (3.) The uniform density of charges made by this process is very favourable to the complete and effective detonation of the entire mass, and to the presence of the uniform amount of moisture in every part of the charge. (4.) Any required density, from the maximum downwards, may be obtained with ease, and any required amount of moisture left in the charge.  These points are of great importance in cases where, like torpedo charges, it is essential to have the centre of gravity of the charge in a predetermined position both vertically and longitudinally, and the charge so fixed in its containing case that the centre of gravity cannot shift.  The difficulty of ensuring this with a large torpedo charge built up from a number of discs and segments is well known.  Even with plain cylindrical or prismatic charges a marked saving in the process of production is effected by this new system.  The charges being in one block they are more easily handled for the usual periodical examination, and they do not break or chafe at the edges, as in