The essential parts of a reaper are: the cutting arrangement, similar in design to that of mowing-machines (except that in many cases sickle-knives in place of plain knives are used); sweep or table rakes to convey the grain to and from the machine; and mechanical means to regulate the delivery of the gavels, so that the size of the same shall be sufficient for binding even in spots or places upon the land where the crop is very light. Many of these machines are constructed so that the various devices for raking, sweeping, gathering, or delivering, may be detached, leaving the machine a simple mower.

The term "Harvester " originated in the Western States, and was applied to distinguish machines which bound the grain from those which simply delivered it in gavels. In Figs. 74 and 75 is shown the Champion mower and reaper, with the names of the various parts marked thereon. The reaping part of the machine consists of the device above the large shoe, which is for operating the rake-arms and the wooden framework, and its attachments whereon and whereby the grain is gathered and delivered in gavels. The chain-wheel is fast to the upright spindle, to which the rake-arms are pivoted or hinged, and is driven by a chain passing around another chain-wheel attached to the main axle of the machine. To the rake-arms are attached rollers running upon an inclined pathway termed a cam. The plane of this pathway is arranged so as to lower the rake-arm to, and lift it from, the table, to rake the grain on to and off from the table-the rake-guide being provided to prevent the rake from contact with the finger-bar.

The rake-arms may be permitted to sweep a gavel of grain from the table at each descent, or may be made to carry the grain on to the table, and allow it to remain there until sufficient is accumulated to form a gavel, when the rake may be allowed to sweep it off. The arrangement by means of which this is accomplished is the switch shown in Fig. 75, operated by means of the treadle-crank and trip-chain shown in Fig. 74. The switch acts to raise the roller-path, lifting the rake-arm and rake before it has time to rake the gavel from the table. When, however, sufficient grain has accumulated to form a proper-sized gavel, the switch moves out of the way, and the rake sweeps the gavel from the table; and in this manner the size of the delivered gavel can be regulated by the operator.

Mr. John Coleman, an English judge at the Centennial Exhibition, says, referring to this class of machines, in his report to the English Government: " A word or two as to table- rakes may not be out of place seeing that this form of reaper is unknown in En.-land. The ordinary sweep-rake is replaced by a jointed rake, which travels in a given orbit on the table or platform, being driven by universal. joint-and-bevel gearing the direction of travel being regulated by a cam screened from the grain by a shield. The advantages claimed for this invention are reduction of draught and superior form of the grain for binding. The rake, when uncontrolled, works continuously but can be arrested at any point by a leverage from the driver's foot. This is a desirable feature, allowing of uniform sheaves for a variable crop. The disadvantages appear to be that, as the rake compresses at the corner of the table, there is some risk of shedding when over-ripe ; also, that the compact nature of the sheaf interferes with the drying influence of sun and wind, so important when grain is cut in a green condition ; and, lastly, the table-rake is not suitable for very heavy crops, especially if the straw is long."

In Fig. 76 is shown the Buckeye mower and reaper, with dropping attachment. In machines of this class a revolving reel instead of sweep-rakes is employed, and the gavels are dropped in the rear of the machine. The duty of the reel is to press the grain to the knives, and hold it while being cut by the "he. The dropper, as the slotted frame behind the cutter-bar is called, is raised at an angle to collect the grain, and is lowered by hand to deposit the gavel.

The Walter A. Wood binder makes a bundle or sheaf to every ten feet, if allowed to work automatically. The binder can be removed from the machine, and the grain bound by hand upon tables attached for the purpose. The amount of duty claimed for a Walter A. Wood harvester with binding attachment is, with fair grain on fair ground, from ten to fifteen acres per day.

In Fig. 77 and 78 is shown the McCormick harvester with self-binding attachment, the latter showing the binding attachment detached.

The details of the McCormick sheaf-binder are represented in Figs. 79-86.

The binding apparatus is fixed at the side of the reaping machinery. The grain as cut is delivered by an endless band to the elevators, shown in Fig. 79, by which it is raised and delivered under the guard on to the platform. Fig. 79 also shows the general form of the binding -arms and their position before inclosing a sheaf. The standard carrying the binding-arm has a reciprocating movement imparted to it, by which it is moved from the position shown in Fig. 79 to the various other positions shown successively in Figs. 80, 81, 82, etc.To put the machine into work, the wire from the upper spool is threaded into the main arm, as shown, and jointed to the wire from the lower spool brought up from under the twister, as shown in the upper part of Fig. 85. The main arm may now be supposed to have moved to the position shown in Fig. 81, and is about to descend through the slot in the platform, and to take the position shown in Fig. 82, at which position the thumb I-seen also in other figures-has moved and passed the other part of the wire, or that from the upper spool, in between the teeth of the twister, so that the two parts of the wire are between opposite teeth in the twister. The standard now begins to return to the position shown inFig. 79, and in its rectilinear movement the teeth of two wheels shown in Fig. 86 engage in a rack by which they are revolved and in their revolution they move the two steel wheels which form the twister and the cutter, a differential movement being given to them by the difference in the number of teeth in the main wheels, so that the twister-teeth gradually overlap after several revolutions by one revolution of the main wheels. As seen inFig. 82, the sheaf is inclosed, both parts of the wire are in the twister-teeth, and the latter now begin to revolve.

Fig. 83 shows the position after the first twist, and Fig. 84 shows the twist completed, and the wire cut off, the wheels having assumed the position shown in Fig. 86, and the standard having nearly returned to the position of Fig. 79. Fig. 80 shows the position of both arms after the sheaf is bound, but before it is released. Each successive sheaf passes the last one off the platform. Now, it will have been seen that the wire has been joined by twisting both above and below the twister, so that, though cut off in one place, the wire is by the join continuous from lower to upper spool, as seen in Fig. 84. When the arm beams to rise again, the lower wire, as seen in Fig. 79, is pulled to the position seen in the lower part of Fig. 85, and as the arm still rises, the wire is pulled in between the twister-teeth, as shown by the light-dotted lines. Now it becomes necessary to get the wire to the position shown in the dark-dotted lines, or to that shown in Fig. 81, and to effect this the twister-wheels receive a half-revolution, obtained by the meeting of a projecting arm and two studs on the main cog-wheels, during the latter part of the return-movement of the standard, which it will be seen carries all this mechanism. The projecting arm thus gives the wheels a push farther round. The wire is now in the position shown in Fig. 79,81, and 86, and the whole is ready to recommence the binding operation.

The following is a summary of the dynamometer tests of sheaf-binders made at the Royal Agricultural Society in August, 1877: