HUNTER'S MACHINE FOR CHAIRING

AND BORING RAILWAY BLOCKS.

Mr. Hunter, of Leysmill, Arbroath, whose ingenious stone-planing machine was described in our Magazine for Oct., 1836, (No. 636,) and which has since that time continued to work with complete success, has lately invented and patented a machine for cutting out in stone railway blocks, the beds for the reception of the chairs, and for boring holes to receive the wooden pins into which the spikes are driven, by which the chairs are fastened to the blocks.

We shall proceed to describe the machines, and afterwards make a brief mention of the success which has attended their operation. Now that it appears to be a question amongst railway engineers, whether stone blocks or wooden sleepers are most worthy of adoption, whatever may tend towards the economical formation of either the one or the other, must be of interest to all connected with this novel and important branch of inland transit. Taking this view of the matter we shall be explicit in our description, and careful as to the authenticity of the statements of working which we publish. The principle of action of the cutting tool, in Mr. Hunter's boring and chairing machines, is precisely similar to that of his planing machine, and its application in the present instance is most ingenious. Fig. 1, is a front elevation of the boring machine; fig. 2 an end elevation; and fig. 3 a ground plan and top section through the line A B of figures 1 and 2. SS SS is the framework of the machine, consisting of four iron uprights and connecting pieces. The top-piece E, composed of two somewhat flexible plates of iron, by having semicircular bends atoo, clasps the boring tools K1 K2, and holds them firinly at the height at which they are placed, by the screws N', N2, N3. M1 M2, fig. 1, are augers of a spiral form, which instead of having centre-bits like the common auger, terminate in two broad-faced points, turning in opposite directions. L' L2 are

male screws, into sockets in the lower ends of which the heads of the augers M1 M2 are inserted and secured. K1 K2 are female screws or sheaths, into and through which the male screws L1 L2 work. The winch or cross-tree R, being placed upon the head of either of the

screws L1 or L3, on being turned, works the auger. G is a railway truck or carriage, for conveying the stone block which is to be perforated, under the boring tools; and HH the rails on which the truck runs. The sheaths K1 and K2 are fastened in the head-piece E, at a height corresponding to the depth of holes required to be bored in the block, by the screws N1 N2 N3.

On examining this arrangement it will be seen, that on the tool being turned, the points of the auger must scoop out or chip off at each revolution a portion of stone, as great, at least, as the distance the screw has descended. Thus, there is no scraping action, (in all hitherto invented stone-cutting machinery found so destructive to the tool,) but, as in the stone planing machine, pieces or chips of stone are removed by the great and steady power applied to the tools. Were the thread of the screw which regulates the descent of the tool very fine, or were the augers merely kept pressed against the stone by a weight or spring, (as has been hitherto tried,) the tool would merely grind away the stone, and at the same time its own edge; but by Mr. Hunter's arrangement the stone must either yield to the descent of the auger, the rate of which is to an extent incompatible with a grinding action, or the tool must break. The chips ascend through the spiral channel of the auger, and are thrown off at top.

The chairing machine is somewhat similar, in general construction, to the boring machine. Figs. 4 and 5, (see our front page,) are front and end elevations. Fig. 6 a ground plan and top section through the line AB of figures 4 and 5. SSSS the framework. The top crosspiece E, is of the form shown in the top section, fig. 6. Z is a sheath, plain on the outside, but tapped through the centre with a female screw, inserted in the top E, and with broad shouldered pieces SS, having orifices e e, so that when the long tails m, of the pins zz are passed through these orifices, the said long ends pressing against the sides of the crosshead F, fix the sheath Z in its position, and prevent its turning. T' is a male screw, which works in the female screw of the sheath Z, and has a cross-piece fixed to its lower extremity, the two arms of which carry the tools or chisels UW and UV. Y is another male screw which

works through a female-threaded cavity in the centre of the screw TT.

y, is

The mode of operation is as follows: the block being brought on the truck and railway under the chairing tools, the centre-bit Y, armed with the tool screwed down by means of the arms b, to the full depth of the chair-seat, and which will give sufficient strain or pressure, to hold the block firmly in its place during the operation of excavating the seat for the chair. The male screw T is then set in motion by the arms a a, the centre tool Y remaining stationary while the tools or chisels UW and UV traverse round it. When the chisels are considered to have penetrated deep enough into the stone, the pins z z, by which the sheath Z is prevented from turning in the cross-head E, are taken out and reversed in the orifices e e-that is, the short tails or ends, nn, are inserted in the ears e e, leaving the long ends m m sticking up; so that the arms a a will, on being turned, press against them, and carry round the sheath Z, and with it all the tools, but without, at the same time, descending, there being no screw on the outside of the sheath. One or two turns thus will grind a smooth face to the bottom of the chair-seat. When the chisels require sharpening, they can be removed from their sockets by loosening the screws d d. Separate and enlarged representations of the tools are given at figs. 7, 8, and 9.

The operations of the chairing and boring machines are carried on conjointly thus:-A railway runs under a set of machines, consisting of two for boring and one for chairing, and the rails are fixed correctly at right angles with the machines. As soon as a block is bored upon its truck, the tools are removed, and the truck with the block upon it drawn by the workmen under the chairing machine, where the chair bed is formed, and the block is completed. By these means the holes are to a certainty obtained at right angles to, and the bottom of the chair-bed parellel with, the base of the block.

With regard to the successful operation of the machine, we have been favored with various documents, from which we have selected the following certificate from Mr. Grainger, the engineer of the Dundee and Arbroath, and Arbroath and Forfar railways :

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Edinburgh, 9th July, 1838. "The machine invented by Mr. James Hunter, of Leysmill Quarry, in the county of Forfar, for boring, as well as that invented by him for chairing, railway blocks, have been in use upon the Arbroath and Forfar Railway for upwards of ten months, during which time more than thirty thousand blocks have been bored and chaired by them. At present four machines are constantly in use in boring, and two in chairing the blocks. By these machines the work is done in a much more perfect manner, and at much less expense, than by hand labour. They have also been employed to a considerable extent upon the Dundee and Arbroath Railway. The blocks which have been bored and chaired by these machines consist of hard sandstone. The holes have been sunk to the depth of six inches; the diameter thereof 1 inches; the bed upon which the chair is to rest is 9 inches diameter, and in point of smoothness is equal to polished work, and is made perfectly parallel to the sole of the block. Five workmen, employed about ten hours a day, finish with ease from 450 to 500 blocks per week.

(Signed)

"T OMAS Grainger."

The above certificate, proceeding from the high authority it does, appears very satisfactory as to the utility of Mr. Hunter's invention. From other documents before us, it would appear that Mr. Grainger speaks under the mark as regards the quantity of work done; the contractors on the railways mentioned are, we are informed, often in the practice of finishing one hundred blocks per day. The cost of a set of machines, consisting of two boring and one chairing, is not more than sixty or seventy guineas.

On the Arbroath and Forfar Railway the wooden pins for plugging the blocks are turned in a lathe, and pierced with a hole, less, of course, than the thickness of the iron spike to be driven in. A much firmer hold is thus obtained with less force of driving, and the great loss by splitting of blocks altogether avoided.

We need hardly observe, that the chairing machine may be easily adapted to cut holes or tubes of any diameter and depth in stone quarries, by steam or any other power, with great speed and

STEAM NAVIGATION TO INDIA.

Sir,-Your correspondent "H," seems inclined to pick a quarrel with me for venturing to differ in opinion from him, and recording my dissent to his views in your valuable miscellany. His last letter produces no change in my opinions, nor does it explain away any one of the facts to which reference was made in my former letters.

I am still decidedly of opinion, that the supineness of our East India Government is affording the Dutch and other nations an opportunity of acquiring a superiority over us, by means of an extensive line of steam navigation in the Indian Archipelago, and that the “steam flotilla" in the service of the company, if not altogether contemptible, is yet quite inadequate to the wants of that part of the British Empire. Hitherto the earnest remonstrances of the mercantile residents, and the strenuous exertions of the East India Steam Committee in England, have failed to produce their proper effect. Individual enterprize has been paralized by an influence which may not be described, and the general good sacrificed to a narrow and mistaken policy. I am not aware that in any part of my correspondence upon the subject of East India steam navigation, that any statement has appeared to countenance

H.'s" misrepresentations of my sentiments, relative to the exertions now making by the Dutch, to establish steam navigation in India for commercial purposes, nor the flourish about the English being "about to reinforce the steam flotilla which they have long ago (sic orig.) introduced in the East Indies from home, by a number of steamers built and equipped in the country itself." Will "H" condescend to inform your readers of the names of those steamers "long ago" introduced into the East Indies from this country? The Enterprize was sent out from this country about twelve years since. What others are there sent out from this country "long ago?" The Atalanta, Berenice, and Semiramis, were sent out last year. The Hugh Lindsay was built in India. If the "steam flotilla' goes on increasing at this rate of five in twelve years, it will be many before it is equal to the increasing wants of India; and will afford, in reality, an opportunity to our Dutch neighbours to

monopolize the steam navigation of the Indian Archipelago.

But "H." charges me with veering round as to the speed of steam-vessels. If he had read my remarks with ordinary attention, such a charge would not have been made by him. In page 98 my statement was, that I had "not at present met with any steam-vessel (meaning, of course, sea-going steam-vessels, of which I was then speaking,) in the course of my somewhat extensive observation, that had been able to maintain such an average speed (10 miles) for several consecutive days."

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"Some few boats will maintain 10 miles `an hour for 30 or 40, or even 80 hours."

Now I still maintain this to be the fact. The Berenice is said to have attained the speed of 14 miles per hour when tried in Scotland, but what was her actual performance when on her passage to India? not ten miles an hour, nor any thing like it. If "H." will refer to the logs of the two vessels as given in the Nautical Magazine, he will find that he is mistaken as to the speed of sea-going steamers, even of the first class; and it must be obvious that he has misrepresented my meaning.

Whilst I am writing this, I have been informed that the Great Western arrived at Bristol on the 7th, having left New York on the 25th ult. This, indeed, would show a speed of rather more than 10 miles an hour; but it is to be remembered that this speed is acquired by a vessel of a very much larger class than any of those formerly afloat, and is in perfect consistency with my remarks in former letters, that with larger ships a greater velocity would be attained.

The Dutch are doing what the East India Government have been openly or covertly opposing-endeavouring to introduce steam navigation for commercial purposes into the East Indies.

The reference to the experimental steamer to be built at Bombay, confirms my previous remarks. 'Strong repre

sentations have been sent home of the necessity for immediately placing a greatly increased number of steamers on this service, and the greatest anxiety is evinced for the accomplishment of the object. The company have at length given orders that the experiment should be tried of building a steam-ship at Bom