Fig. 8. Gruben-Krenz Boring Machine before being placed on its Bearings. Fig. 10. Electrically-operated Lathe. Separate Motor Belt-driven. Fig. 12. Portable Electric Motor for operating Machine Tools. fixture mounted on this same support was being used to drill a series of radial holes in the rim of the wheel. This shows the wide range of work to which a machine of this type can be adapted. It will be noted that the flywheel is driven by the very simple means of passing a steel rail between the spokes of the wheel and bolting each end of the rail to one of the arms of the frame.

Fig. 11 shows the same machine in operation upon the generator frame and the controlling rheostat and starting box of the motor are to be seen in front near the main bearing.

In certain parts of a factory where small tools are used, and frequently a number of them requiring in all but a small amount of power, it is generally conceded that a single motor can be used to advantage in each of such rooms, driving a short line shaft, or if more than one line of shafting is necessary, a motor for each transmission. There are two such rooms at the Oerlikon works, with single polyphase motors for

Fig. 9. Boring Machine working on Heavy Field Magnet Wheel.
Fig. 11. Boring Machine working on Stationary Armature.
Fig. 13. Experimental and Testing Department.

each line of shafting, mounted upon brackets and shelves on the end walls of the rooms near the ceilings, and transmitting the necessary power by belting. In these rooms small parts, such as brush holders, are made, and punching machines are used for punching out armature disks.

One of the most important departments of any manufacturing plant should be its experimental shop, for testing the output of the factory to see that every machine tool, electricallydriven or mechanically-driven, is perfect in every way; also for testing its capacity, for determining its efficiency and the necessary amount of power required to drive it. These fig. ures should be exactly given and marked upon the shipping tags. Such an experimental room is shown in Fig. 13, and this is where the necessary power is determined, temperature rise of the machine tool motors found out, and efficiency of motors and dynamos tested.

Before closing it may be of interest to give a short de

scription of the power plant. It has in reality two central power stations, one supplying current from a steam-driven plant at the works, and the other located at Hochfelden, 22 kilometers distant, where a hydraulic electric power plant has been in operation some time, furnishing the necessary current by vertically driven generators for operating a large proportion of the machinery at the Oerlikon Works. The necessary water for driving the turbines is supplied by a tributary of the River Rhine known as the Glattflusse, which is an outlet of the Greifensee near Zurich, Switzerland. The water is conducted from a large dam at Hochfelden, a distance of 2.5 kilometers, to the turbines which operate under a head of 11 meters, the maximum flow of water being 5,000 liters per second. Each of the turbines has a capacity of 275 H. P., and each is directly connected to a Drehstrom generator having a vertically revolving shaft. The voltage of these gener ators is 58 volts and the speed, 180 revolutions per minute. There are two exciting direct-current generators, each directly connected to its own turbine and each capable of supplying the entire excitation current required by the alternators. Three step-up transformers are used, with a ratio of 1:154, raising the voltage of the alternators at 58 volts to a high tension line potential of 15,500 volts. After this polyphase current is transmitted over the transmission line 22 kilometers long at this high potential. Step-down transformers are installed at the Oerlikon Works, having a ratio of 53.3:1, the tension being reduced from 15,000 volts to 135-140 volts, at which pressure it is conducted through cables to the various motors about the works, including the electrically-operated cranes. These cranes are equipped with three-phase alternating current motors, 3 trolley wires or conductor rods being used with the three necessary contact devices upon the cranes.

The high-tension conductor coils of the transformers at Oerlikon consist of 2,772 turns of copper wire 3.3 to 3.7 millimeters in diameter, and the winding is connected in 11 sections, each of which has 252 turns. The three coils have a total weight of 800 kilogrammes, and a total length of wire of 3,500 meters is used in construction. The low tension coils are simpler, two being used for each phase connected in series. Each coil has 52 turns consisting of 10 copper conductors in parallel of 7.3 to 7.8 millimeters section.

It became necessary as the output increased to install a steam power plant, and eight steam engines were installed ranging from 45 H. P. to 600 H. P., with a total additional capacity of 1,220 H. P. The necessary steam supply was obtained by a boiler plant, seen in Fig. 2, consisting of six boilers, including four Cornwall boilers, two of which have a heating surface of 75 square meters (807.3 square feet) and the remaining two 65 square meters (699.6 square feet) and 100 square meters (1,076.4 square feet). Three of the boilers operate at a steam pressure of 6 atmospheres (88.2 pounds), and the last at 10 atmospheres (147 pounds). In addition to the above there are two larger boilers seen in the background in the illustration, each of which has a heating surface of 160 square meters and operating under a pressure of 11.5 atmospheres.

The boiler plant is equipped with Green economizers having 144 tubes 2,750 millimeters long and 115 millimeters in diam eter. These are arranged in two groups, each of twelve elements consisting of six tubes each. Worthington pumps are used for feeding the boilers. The chimney is 36 meters high, and has a diameter of 3 meters.

The engine and generator room is shown with its switchboard equipment in Fig. 3. The 600 H. P. triple-expansion borizontal engine, constructed by Sulzer, is of the condensing type, and operates at a pressure of 11 atmospheres (161.7 pounds). The speed of the engine is 94 revolutions per min ute. It drives a three-phase Oerlikon generator supplying in each phase a current of 1,500 amperes, the potential being 135 volts. The 200 H. P. horizontal engine, of the Sulzer compound type, with a speed of 65 revolutions per minute, operates a large three-phase Oerlikon alternator, and the exciting current for the fields of these alternating-current generators is obtained by dynamos directly connected to the vertical compound engine seen at the left in illustration, Fig 3. These machines operate at 900 revolutions per minute and supply a continuous exciting current of 70 amperes at 125 volts.

The current for lighting the entire works is supplied by direct-current machines, 135 volts being the potential at the switchboard and 125 volts at the lamps. There are 1,400 incandescent lamps used, of 16 c. p. each, and 286 arc lamps, each pair of the latter being connected in series. The 100 H. P. engine opposite the switchboard has directly connected to it on either side a continuous current dynamo, these two generators being connected in series. Several other units are also installed and in operation, the large number of units being largely due to the gradual growth of this great engineering plant. The annual output from the foundries of this establishment in the way of cast iron and cast steel is said to be more than three million kilogrammes (3,300 tons).

NOTES ON CURRENT TOPICS.
JAMES VOSE.

Among the tendencies of the last year or two in the district of Manchester, England, may be noted the growing popularity of vertical boring and turning mills and disk grinders. Among local tool builders who have recently made rather a specialty of this work may be mentioned Messrs. Smith & Coventry, Geo. Richards & Co., Ltd., and John Hetherington & Son, Ltd., in the larger sizes, and Roberts Bros. in the smaller. Further afield are J. Butler & Co., of Halifax, and Webster & Bennett, of Coventry. Messrs. Cunliffe & Croom, Ltd., and Roberts Bros. also manufacture some disk grinding machines which appear likely to find a special field of usefulness in the manufacture of textile machinery, a large number of small brackets and details used therein lending themselves admirably to this method of finishing. The output of the machine is found to compare extremely favorably with that of highly-specialized manual labor, and much more appears likely to be heard of this branch of tool development. The general utility of the horizontal boring machine is also obtaining rapid recognition, and Geo. Richards & Co., Ltd., Manchester, are assisting the process by the remodeling of their Nos. 1 and 2 machines. These tools are now made with two back-gear ratios, which, by the use of the twospeed countershaft, give 24 speeds to the spindle; positive feed with six quick changes, on Hendey-Norton lines; power rise and fall of the table; considerable traverse of spindle and great handiness in general, at a price calculated to encourage inquiries. Working in harmony with the Richards Tool Co., of London, they are also producing side planers embracing many improvements in general design and detail. The increasing desirability, in the case of heavy work, of bringing the tool to the work, in place of the reverse process, is not escaping the notice of tool builders here. The Atlas Engineering Co., Manchester, have recently devoted special attention to this branch.

Another local development is the placing on the market by Mr. John Tangye, who has had considerable experience in this class of work, of a line of rotary planers. One size, which he first built to suit the writer's requirements, has met with a good reception at the hands of users. We must confess to a distaste to setting work on a vertical surface, and a swiveling angle plate vise was designed for this machine to ob viate the necessity of such, which answers its purpose very well. The proper supporting of slender flat work during machining is of considerable importance, and this is accom plished by the provision of numerous easily adjustable sup porting points and special down-nip jaw dogs. The tool will machine a surface 30 by 11 inches, and on suitable work will show a time saving of 50 to 75 per cent. An efficient friction feed capable of fractional variations within wide limits is a feature of the machine. Self-hardening steel cutters of a section giving suitable rake and clearance and individually adjustable are used, and by removing two of the cutters while roughing out and replacing them so they will project slightly further than the roughing cutters for the finishing cut a very smooth finish may be produced. Personally, we find the plan of taking, say, three cuts at the coarsest traverse (say 5-16 inch) better than taking only one or two with a finer traverse. A demand having arisen for this type of machine arranged by means of a hollow spindle, bored to Brown & Sharpe taper, and a removable supporting arm, to act as a

plain milling machine, Mr. Tangye is producing an interesting line fulfilling these conditions, and also larger sizes designed to surface areas 24 inches by any length.

The British Westinghouse Co's new works at Trafford Park are now on the point of completion and are rousing much interest, the fact of their being intended to be worked "on American lines" causing some speculation as to the ultimate effects of such action on the points of view of British employers and workpeople. For our own part, we fancy the effect will be almost wholly good, as there appears little of mystery in the reasons for American success in many industrial matters. The Americans have simply known exactly what they wished to do, and have gone the most direct way they could find to accomplish it. They are seldom impeded by the peddling modes of thought engendered in the case of some British firms by a gradual rise from very small beginnings. Trafford Park which covers a large area contiguous to the Manchester Ship Canal, and connected to the main railway systems of Great Britain, promises to become a very considerable center of engineering, especially of those branches bearing on electrical developments. Altogether the rapid expansion of engineering industries in the Manchester district is in itself sufficient answer to any pessimists in our midst who fancy the success of any other country in any line a direct menace to our own prosperity, as though any country could be enriched by the permanent downfall of its customers. The fiscal policy of the United States, by which it apparently endeavors to sell to this country without affording us the opportunity of return trade on an equitable basis, is arousing a sense of resentment, as the States by keeping up their practically prohibitive duties seem to give the lie to their assertion that they are able to compete with the rest of the world in manufactures in general. The British people do not wish to impose retaliatory duties. All they ask is "a fair field and no favor."

RECEIPT FOR SILVERIMETAL.

A writer in the Aluminum World gives the constituents of a hard alloy which has been found very useful for the operating levers of certain machines. The spacing lever of a typewriter is constantly handled when in use and if made of iron or steel and nickel-plated, even heavily, the plating soon wears off, leaving the metal underneath exposed to rust and corrosion, a condition which, of course, is not permissible. If the levers are made of brass the matter is not helped to any extent, as the plating wears off the same as iron or steel and leaves the brass exposed which is, if anything, more objectionable than iron or steel. The metal now generally used for this purpose by the various typewriter companies is "aluminum silver," or "silver metal." The proportions are given as follows:

This alloy when used on typewriting machines is nickelplated for the sake of the first appearance, but so far as corrosion is concerned, nickeling is unnecessary. In regard to its other qualities, they are of a character that recommends the alloy for many purposes. It is stiff and strong and cannot be bent to any extent without breaking, especially if the percentage of aluminum is increased to 3.5 per cent; it casts free from pinholes and blowholes; the liquid metal completely fills the mold, giving sharp, clean castings, true to pattern; its cost is not greater than brass; its color is silver white; and its hardness makes it susceptible of a high polish.

Knife grinding extraordinary is that done by the special grinding machines made by the Bridgeport Safety Emery Wheel Co. The largest knife grinding machines built by this company grind knives 170 inches long for "gulleting" machines used in tin and sheet metal mills for shearing thin metal plates. These machines are largely used in the sheet metal mills in the vicinity of Pittsburg, Pa.

WORKSHOP WORDS AND THEIR ORIGIN. W. H. SARGENT.

AMBA, the jester in Ivan

hoe," calls attention to the fact that the names of live stock are Saxon so long as they require care or represent labor, but when dressed for the table they are called by aristocratic Norman or fashionable French names. Even in our own time the same distinction may be traced. The short, strong, direct work-a-day words are Saxon, as "anvil," "sledge," "saw," "lathe," "nail," "spade" and "plow." These are a part of the vocabulary of the working class, while the newer words like "bicycle," "automobile" and "telephone" belong to people of leisure who have time enough to pronounce long names of Latin origin. When these words come to be used for what they represent rather than for their scientific accuracy they are shortened to "bike," "mobile" and "'phone." The many-syllabled words are usually built up out of parts of other foreign words so as to accurately describe the distinctive features of the object. "Locomotive," for instance, coming from the Latin locus, place, and motum, to move; "safety valve" is from the Latin salvus or French sauf (safe) and valvus, a leaf; "gas" is from the German geist, to blow, and because of its airy and unsubstantial character we have our word "ghost" from the same root.

The Romans spoke of "ironing a horse" instead of shoeing, much as we noW say "ironing a carriage," and as ferrum was the Latin for iron we come to have "farrier" for horseshoer. And speaking of horseshoer, what a volume of history, what a record of progress is locked up in the word "marshal," the commander in chief of the French army, since he, too. was once but a maréchal or horseshoer!

.

There are histories, as well as sermons, in stones. The ancients used small pebbles as an aid in counting and performing other arithmetical operations. These stones were called calculi, from whence naturally comes our word "calculate." The word "scale" (weighing machine) is unique in that the word comes down to us through two distinct channels, entirely unconnected. The Anglo-Saxons weighed in an even balance, using clam shells for pans. These shells they called "scalu" and the balance, in course of time, came to be called a "scale." The Romans improved upon this primitive balance by adding a sliding poise and by graduating the steel-yard into "scala"; that is, steps or divisions. Thus the

word "scale" came to be applied to any graduated scale, either of measurement or of weight, and finally for the second time the weighing machine itself was called a "scale."

The word "templet," or more properly "template," is from the Latin templatus, vaulted, since the masons, then as now, used a wooden form or "template" for laying the arches in a vault. Gradually the name came to mean any form used in laying out or constructing work. Eccentric is straight Latin, being from ex, out of, and centrum, center, "off center." Petroleum is from petra, rock, and oleum, oil, and tells its own story very neatly.

Conversely "manufactured" originally meant "hand made," and has since changed about so that it now means almost the opposite, because certainly no large part of the "manufactured" products of to-day are "hand made." We still speak of a shop as employing so many "hands," although we mean, of course, that not only the workman's hands are utilized, but his arms and legs, his eyesight, his brain and all his faculties of mind and body. Other familiar words have completely changed in meaning. "Crafty" formerly meant having a craft or trade. "Villain" was once one who lived in a village. "Rubbish" was the refuse which had been rubbed off and thrown away. "Lumber" takes us back to the time when the Lombards did a general mercantile and banking business all over Europe, a "lumber yard" or Lombard yard being the place where their goods were stored.

The "haft" of a knife is the part by which we have to hold it. A "tinker's dam" has not the profane meaning sometimes attached to it, since it once meant a dam of bread or putty around the work which the tinker was soldering, the same as the plumber of to-day forms a mold around cast iron pipe when running a lead joint. A thing is, therefore, "not worth a tinker's dam" when it is of no more value than this cast-off form or mold which has been used and thrown away.

Many names are given because of the resemblance between the article and some object with which we happen to be familiar. In "dovetail," "bull's-eye" and "butterfly nut" the resemblance is so marked as to need no comment. A "spider" looks the part. A "ram" was born to push and bunt, and the Romans carved the prows of their boats and poles of their chariots to resemble the head and horns of a ram. A "snibel," or snipe bill, is a term sometimes used by blacksmiths to denote a swivel nut and hook. An "alligator wrench" so resembles the toothed and gaping mouth of the alligator that the name seems appropriately applied. This reptile, in turn, received his name from the Spaniards, who, when they first saw one, exclaimed "el lagarto"-"the lizard." Some English sailors who were on board adopted the word, which they mispronounced "alligator," and the hideous reptile has since borne this name.

"Pig iron" used to be molded in the sand in short fat bars a few inches apart, all attached to a main runner or "sow" from which they derived their supply until filled. In this condition they presented more than a fancied resemblance to a litter of sucking pigs attached to the mother sow. The suggestion was too evident to be overlooked and the name "pig iron" was applied and will doubtless always cling to iron in this form, although it is now cast rapidly by elaborately designed machinery with no suggestion of the pig-pen.

Many people received their name from the trade or calling with which they were connected. "Jenner" was once a joiner. "Webster" was one who made webs; that is, a weaver. "Currier" was once a worker in cuir, or leather. The old joke has it that the "Smiths" were all produced by the "Smith Manufacturing Co.," but older than this is the fact that the "smith" was one who smiteth, a goldsmith or silversmith being one who beats or smites the metal with the hammer.

There is a record of invention and a history of commerce locked up in the words which are derived from the names of places or of people. "Copper" derives its name from the island of Cyprus, once so rich in mines of this valuable metal. "Magnet" has its name from the deposits of iron ore in Mag. nesia, Asia Minor. "Tramway" recalls the name of its inventor, Outram, and "galvanism" perpetuates the memory of its discoverer, Galvani. "Maximite" is not so named because it is the maximum or greatest of all explosives, but rather

because its inventor bore the name of Maxim. These studies into the origin of names should teach us the value of the correct use of words. A "smokestack" is a chimney or stack of brick or other masonry for conducting smoke. Any metal pipe for this purpose is properly, therefore, a smoke pipe and not a smokestack. The latter is, however, in such common use and its meaning is so evident that it is usually accepted without criticism. We speak of a "bevel" as being any angle whatever, but properly it is any angle other than 45 or 90 degrees. A "dock" is an enclosure into which a vessel is received and not the surrounding piling or wharfing. To speak of "falling off a dock" is equivalent to saying "falling off a hole!"

A "pair of scales" is incorrect, since only one is meant. A "pair of calipers" is a corruption of a pair of calibers, but is now in such common use that the original form is obsolete. We have used "rosin" for "resin," "shear" for "shore," "spile" for "pile" until both are in common use, and who shall say that one is not as correct as the other?

THE OLDEST STEAM ENGINE NOW AT WORK. Last summer, much to one's surprise, while at the Glasgow Congress of Engineering, and directed by the excellent handbook prepared for the guidance of members of the Congress, a real live Newcomen engine was discovered at a colliery at Rutherglen, near Glasgow. It is almost certainly the oldest engine now at work and is really a quite remarkable case of the survival of the unfittest.

A few years ago an engine of James Watt's manufacture, with sun and planet wheel complete, was taken down at a London brewery. It had been continuously working for 102 years, and was not at all decrepit when dismounted. It now forms an archæological exhibit in the museum of Sydney University. But this engine, though interesting and of about the same age as the Glasgow Newcomen, was of a comparatively modern type. It did not represent an extinct race.

The Newcomen engine at Farme Colliery, Rutherglen, was built in 1809, and has worked continuously to the present time. As it was constructed long after Watt's invention of the separate condenser, it may, perhaps, be inferred that one object in its design was to escape payment of royalty. Curiously enough, unlike all other Newcomen engines of which there is record, it is a winding, not a pumping engine. The cylinder is of pure Newcomen type, but there is a modified Watt parallel motion with the radius bar above the beam. and a crank and flywheel of comparatively modern type.

The cylinder is 31⁄2 feet in diameter, and the stroke 6 feet. It takes about thirty-five seconds to raise coal from the bottom of the pit to the ground level. The cylinder was never bored, but it has now a beautiful internal surface, having worn out probably a thousand packings. The piston is packed with hemp gasket, and carries a layer of water on top, which makes it quite steam tight. There is no automatic valve gear. A single handle, worked by a man, opens alternately the steam and injection valves. There is no air pump Gravity and the pressure of the incoming steam drive out the condensed steam and injection water through a flap foot-valve. It is stated that except brasses and one or two spur wheels. broken by accident, no important part of the engine has been renewed since it was built.

The beam is about 17 feet long and the flywheel is 15 feet in diameter. There is a feed-pump worked from the beam. The latter is carried on a masonry pier. The engine works quite smoothly and well, and, strange as it may seem, it is probably, for the intermittent work it is doing, not so ex travagantly wasteful as might be supposed.-W. C. Unwin, in Cassier's Magazine for March.

H. T. Potter, Leonardsville, O., writes: "I noticed MACHINERY described an axle oiling device in a recent number, in which the axle was oiled by means of radial holes in the axle connecting with a longitudinal hole, into which oil was forced at the outer end of the axle by an oil pump. We have used compression grease cups screwed into the hub of the wheel and use hard oil' or axle grease with good satisfaction. The holes do not gum up nor does the grease run off when this method is used."

ELECTRICALLY-DRIVEN MACHINE TOOLS.-4.

PLANERS DRIVEN BY MOTORS-THE PROBLEMS ENCOUNTERED.

A. L. DE LEEUW.

Planing machines form a class entirely different from the machines treated so far. In boring machines, either the work or the tool has a continuous rotating motion; in planing machines, the work or the tool has a reciprocating motion, and, in most cases, alternately at a higher and a lower speed. Various methods are used for producing this motion. In most pillar shapers, for instance, the required motion of the tool is produced by a shaft running continuously in one direction, and acting on a pivoted lever. In a great many travelinghead shapers, and also in most slotters, this motion is produced by what is known as Whitworth's quick return; but in the great majority of cases, namely, in planers and large slotters, the desired result is obtained by shifting belts. Where a shaper or crank slotter is to be driven electrically the problem becomes a simple one, because all that is necessary is to substitute a motor for the motive power, which otherwise drives the continuously running shaft. Of course this problem is perhaps not so easy to solve; but what I mean is this, that there are no difficulties beyond those mentioned in my previous articles.. A small pillar shaper, for instance, is generally driven by a cone pulley with three or four steps, and no back gearing, so that the speed variation

smaller shapers and slotters and proceed at once to those planing machines which are driven by shifting belts.

Every mechanic is, of course, familiar with the planer. In fact, I am almost afraid that most of them are so very familiar with this machine that they fail to notice some of its most peculiar features. The ordinary, present day planer acts by moving the work against the tool. It therefore has a platen, or table, capable of sustaining heavy loads, and of having these loads clamped down to it without springing or distorting to an appreciable extent. It follows that this table must be of heavy section, and therefore of great weight per foot length; besides, most planers are made long enough to plane long work, or sometimes a great number of shorter pieces. The weight of table and work together is often very considerable, and this weight has to be moved against sliding friction, both while doing work and while reversing. To show what a large factor this weight is, in the power required for a planer, I will take an example of an actual planer which I have seen at work many a time. This planer will plane work 12 feet wide, 10 feet high, and 30 feet long. It has four heads, two on the cross rail and one on each housing. The table weighs about 65,000 pounds, and I have seen it at work with a load of 80,000 pounds. This planer has a cutting speed of 20 feet and a return speed of 50 feet per minute. Now suppose the coefficient of friction of the table upon its ways to be 10 per cent (it may be higher with poor lubrication), then the pull required to move this

in such a machine is not very large, and a variable speed motor with a moderate range of speeds will be all that is required. The same is true about the smaller traveling-head shapers and the smaller slotters. In the larger machines of these classes, back gears are used; but the cone ratio is generally not very large, and here again a motor with a moderate speed range would do. It is easy to understand why this should be so. Take, for instance, an 18-inch shaper. The longest stroke, of course, is 18 inches. The shortest stroke, which one would expect to use, is certainly not less than 3 inches, which gives a range of six to one. Add to this 66 per cent for variations in speed, due to difference in hardness of material to be cut, and you get a total speed range of ten to one. One can get this by taking a motor with a speed range of three to one, and a back gear ratio of three and a third to one. Of course, as I stated before, it is sometimes pretty hard to get this range of three to one in a motor; and we will have to fall back on some mechanical device for supplying this speed range. Of such devices, I have already mentioned two sets of back gears, sliding gears, change gears (and combinations of all these), and variable speed countershafts. Other devices, applicable to the smaller machine tools, are pull pin gears, a cone of gears (such as used for the feed of a Hendey-Norton lathe), and various so-called speed controllers which are in the market. As the problem of the electric drive of such machine tools is not essentially dif ferent from the problems treated so far, we may dismiss the

table is (65,000+80,000): 10 14,500 pounds. Suppose, further, that all four tools are at work, each requiring, say 8,000 pounds pull-which, by the way, is pretty heavy cuttingthen the pull required on the cutting stroke is 14,500+ (4 X 8,000) 46,500 pounds, and on the return stroke only 14,500 pounds. As the table moves 20 feet per minute on its cutting stroke, the power required on that stroke is 46,500 X 20= 930,000 foot pounds per minute, or about 28 H. P. As the table moves 50 feet per minute on its return stroke, the power required when returning is 14,500 X 50 725,000 foot pounds per minute, or about 22 H. P. It must seem strange that this planer requires almost as much power to reverse as when doing very heavy duty, but experience shows this to be the case. If this planer had been doing light work, say finishing a piece with one tool, requiring perhaps 2,000 pounds pressure, the power required for reversing would still have been 22 H. P.; but the power required for cutting would have been only (14,500+ 2,000) X 20 330,000 foot pounds per minute, or 10 H. P.

=

Ever since planers were driven by electric motors, it was noticed that a great excess of power was required at the moment of reversing, especially from the cutting stroke to the return stroke. I do not doubt but that it was noticed before, only this phenomenon did not present itself in such an objectionable way as when a motor was used. The motor would spark and heat, and burn up brushes and commutator, and do all kinds of tricks calculated to make a man think,