The forging of these parallelopipeds, surface-plate?, and similar implements, of granular Bessemer steel, has been described in the third chapter; it is therefore necessary to now mention only the planing and lining of such articles. The right-angled block shown by Fig. 617 is one of a set consisting of two, three, four, or any other required number of such tools, which are first forged either singly or in one long bar to be cut into short pieces, each of the desired length. Those that are forged singly are especially adapted for hand-planing, which consists in entirely planing the object with chiselling, grinding, filing, and scraping, without any machine-planing. A single block which is to be thus treated should first have one of its broad sides properly planed with smooth filing, and with reference to a standard plate. The plane thus first made becomes the primary, to which the opposite broad surface is to be made parallel, and the four adjoining surfaces made at right angles. Marking the block is next performed, and this can be properly done, because the primary plane is already produced. To quickly mark the place of the opposite broad surface, the work is put upon a table with the primary plane in contact, and a scriber-block is used to mark four straight lines, one upon each of the four sides that are at right angles to the primary plane, and therefore at right angles to the table's plane surface. While the block is thus situated, its primary plane is analagous to the primary plane of the block in contact with the table in Fig. 621, or to that in Fig. 628; and by adjusting the scriber-point to a proper height above the table, the four lines are made to denote that particular dimension of the block, and also to indicate the boundary of the hidden plane to be formed parallel to the primary. If pairs or sets of blocks having the same dimensions are being made, one broad side of each block should be first planed, and the opposite broad plane of every block next marked at one operation ; this is effected by adjusting the scriber-point to the desired height, and scribing all the blocks without altering it. By this means the same dimension on each block is accurately indicated, and also without trouble.

This marking can be done also with a calliper, although such marking is far inferior to that of a scriber-block. If a calliper is to be used, the feet or points are adjusted to the desired distance from each other, and, while held in one hand, one calliper-point is put into contact with one edge of the primary plane at the same time that the other calliper-point is put upon the surface to be marked ; while in this position the calliper is moved along, and a line is marked which is straight, because one calliper-point is in close contact with the primary plane, and this point is therefore a sort of guide to guide the other calliper-point which marks the line.

After the block or blocks are marked, the superfluous metal which is outside of the lines is filed off, or first chiselled off, if a sufficient amount exists to require chiselling ; and the reduction commences by first bevelling the edges to the gauge lines by means of a rough file, similar to .the mode of bevelling a cylindrical block. A right-angled block having one of its sides thus bevelled is shown by Fig. 625, and if much is to be cut off, a few grooves are made across while in a vice, as seen in Fig. 631, the end when grooved appearing as in Fig. 632. In Fig. 628 a block is shown with the boundaries of its hidden broad plane sci-ibed, and is therefore ready for bevelling and reduction, in order to produce the hidden plane, whose boundaries only can now be indicated. During all such chiselling in a vice, the place of the cut must be as near as possible to the top of the vice, because the chisel cuts best at the place of greatest resistance, which is at the top edges of the vice-jaws; consequently, the work is placed as low in the vice as circumstances permit.

As soon as both the broad planes of the block are produced, and made tolerably parallel to each other, the two long narrow sides are chipped or filed, and made square to the two broad sides or planes. To make them right angular, an el-square is necessary, and this is used either with or without a surface-table, according to circumstances. If a standard table is accessible, the block is put upon the surface with the two broad planes at right angles to the surface; and in this position a scriber-block is made to scribe a line upon each broad plane, which will indicate the boundary of one of the narrow planes to be produced. The next step is to put the block upside-down, and mark two more straight lines upon the same broad planes, but at the opposite edges, the block remaining with its broad planes at right angles to the table as before. This scribing can be properly done only by carefully fixing the block so that its two finished or nearly finished planes are exactly at right angles to the table; it is therefore necessary to mention how this right angular position is obtained.

At the time the block remains on the table with one of the rugged narrow sides in contact, three or four little smooth steel wedges are put between the work and the table, and they are gently hammered in or pushed in while an el-square's blade is near the block's planed broad side, and the square's pedestal rests on the table. Through the square being thus situated, the operator can see which particular wedge or wedges require pushing in further, to put the broad sides into the desired position; and when the el-square denotes that a right angular position is obtained, the scriber-point is adjusted to the proper height, and the scribing performed.

The block being thus marked, is ready for bevelling and filing to the gauge lines, to produce two more planes, and if the scribing has been properly done, and only very thin marks made into the block, the four planes will be very near to the required right angular positions, but will afterwards need a further squaring with reference to an el-square. The extent to which this squaring is conducted need not be sufficient to entirely finish the surfaces, because the work may get bruised or damaged in some way, by fixing it in the vice with rough or dirty clamps; consequently, it is advisable to finally file and scrape the block when all its six planes are produced. The degree of precision to which this final adjustment of the planes to right angles may be conducted, depends on the accuracy of the standard square, or standard right angular block which is used for adjustment; and also on the particular idea existing in the mind of the operator concerning a right angle and a plane; for it is of little use to provide an operator with good standards unless he has a delicate perception of the purposes for which the standards are made, and of the ideal angles and planes represented.

The two smallest planes of the block are those termed ends; these should be the ones last produced, and the final scribing is that which denotes the boundaries of these planes, which exist in the block, although hidden by the rugged exterior, in a condition similar to that of the original state of the four planes now formed. A block having four planes and two rugged ends is shown in Fig. 627, where one end of the block is seen nearest the table, and resting on a wedge, wedges, or packing of some sort, that the planes may be put at right angles to the table, the method of adjusting being similar to that described for adjusting the two broad planes first made. But through four planes being now produced, additional care is now requisite to apply the blade of the square to all the four surfaces ; and when the right angular position is obtained, the marking is performed by scribing four lines this time, upon the upper part of the block, instead of only two, each of the four lines being on one of the four planes. When marked, the block is ready for reducing at the scribed end, and when the hidden plane at this end is produced, it is put into contact with the table's face, and the boundaries of the plane at the opposite end are scribed; not, however, without applying the el-square, as before, because the small plane just made may not be very near to a right angular position to the four planes adjoining. If the square now detects a small divergence from a right angular position, a piece of thin paper is put under one edge of the block, to effect the requisite alteration. When this final scribing is completed, and the block reduced to the lines, the places and positions of all the six planes have been determined, and are now produced; consequently, the planing and lining of the work for producing the previously hidden planes, is effected.

The lining of three, four, six, or any considerable number of right-angled blocks, for hand-planing, consists in placing several together on a table, as in Fig. 626, after planing, or partly planing, those sides that are to be in contact with the table, whether they are broad sides, narrow sides, or ends. If four, six, or any other number of blocks are thus placed, the scribing of all is easily accomplished at one operation, as shown by the scribed lines in the Figure.