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THE CIVIL EXGIXEER AND ARCHITECTS JOURNAL. 



[OcTOBBB, 



ends simultanodusly; 'tut vilien the enf;ines had been at work for 

 a short period, it wiiij observed the tuhe had got into a tremuk)us 

 motion like a wave. In consequence, this operation was stopped 

 iind a consultation held, when it was considered that it was oc- 

 casioned by working the pumps at each end of the tube simul- 

 taneously, and it was decided to work the engines at each end al- 

 ternately: by uilopting this mode, the motion was got rid of. — Mr. 

 Stephenson believed the fracture took place in consequence of the 

 unequal cooling of the iron at the angle of the press at F; he has 

 therefore decided upon having two cylinders cast in some other 

 form, — one, as shown at iig. 2, with a spherical bottom, the same 

 thickness as the cylindrical part; and the other, as shown in iig. 3, 

 with an open bottom, and a plate made to close the opening: but 

 it is intended to use one of them only. Mr. Stephenson said some 

 strong comments had been made because he allowed a faulty cylin- 

 der to be used — this was not the case; the original fault was a leak 

 which aj)peared in the neck of the cylinder, where an accident 

 could not take place. This leak was easily stopped, and did not 

 in any way cause the accident: the part that gave way was at the 

 bottom of the cylinder, and the other at the top. 



Remarks. — Mr. Roberts observed, the way to prevent the oscillation or 

 tremulous motion in the tuhe was to work the engine as irregularly as possi- 

 ble. He considered the shape of the press was bad for casting, and that the 

 best mode of casting had not been adopted. It would greatly improve the 

 strength of such work if spiral casting were adopted — that is, to pass the 

 molten fluid into the mould in a tpiral direction. 



Some interesting observations were made by Dr. Robinson, Professor 

 Willis, and Mr. Webster, on the cause of the oscillation and the severe trial 

 it caused to the presses ; they considered the accident might have been oc- 

 casioned throigh pulsation of the press, arising from the oscillating motion, 

 however small, of the tube. 



7. Oil the Siijirriority of Macadamised Roads for Streets of Large 

 Towns. By J. I'icott Smith, Surveyor to the Commissioners of 

 the Birmingham Street Act. 



There is a very prevalent and very natural feeling against the 

 employment of broken-stone roads for streets, because, as they are 

 usually managed, they are the cause of very great inconvenience 

 to householders and others by the great dust and dirt they occa- 

 sion, and also because their maintenance and repairs are very 

 expensive, while the draught of vehicles upon them is very heavy. 



The object of the present paper is to prove, from long-continued 

 experience on a large scale, that those objections do not necessarily 

 accompany the use of such roads, and to show how the inconveni- 

 ences may be most completely and economically avoided. 



This subject has been a matter of careful study to me for many 

 years, during which I have had under my immediate charge 107 

 miles lineal of street-road, being an area of about a quarter of a 

 million of square yards of macadamised surface, and also the 

 general superintendence of a considerable extent of turnpike 

 roads. The result of this extensive and continued experience 

 has been to convince me that broken-stone roads, if properly con- 

 structed and managed, and well cleansed and watered, are the best 

 adapted for the streets of a large town of any description of road 

 yet tried. 



Of whatever nature the surface of a road is to be, it is essential 

 that its foundation should be of firm material, well consolidated 

 and perfectly drained; if not, the crust becomes loosened and 

 destroyed, the road is rough and uneven, and wears into holes 

 and ruts. 



Having obtained a good foundation, the next point ia to cover 

 it with a hard compact crust, impervious to water, and laid to a 

 proper cross-section. The stones must he broken to one regular 

 size, well raked-iu, and fixed there by a binding composed of the 

 grit collected in wet weather by the sweeping-machines, and pre- 

 served for this purpose. This binding must be laid on regularly, 

 aiid watered until the new material is firmly set, which it will do 

 very quickly, and with the regularity of a well-laid pavement: 

 the sharp angles of the stones are preserved, and there is both 

 great saving of material and a firmer crust formed than by the 

 common method of leaving the material to work into its place 

 without the use of binding, — in which case, the angles of the 

 stones are worn off and reduced to powder, and at least one-third 

 of the material wasted in forming a binding in which the stones 

 may set. By the improved method the binding is formed of ma- 

 terial that would otherwise be uselesa. 



A practical illustration of the principle 13 evidenced in the street 

 leading from the railway station in this town (Birmingham), which, 

 from the great wear and tear to which it is subject, I found neces- 

 sary to summer coat. This was done on the 28th of August ult.; 

 on the 29th the binding was laid on; and on the 1st of September, 

 it was well washed and cleansed by the machine, ajad presented a 



surface well consolidated, firm, and level: thus in five days was 

 accomplislied what under the old method would have required 

 three months. 



In the common method, not only is there great waste of mate- 

 rial, but the loose stones occasion delay by their resistance, great 

 fatigue to the horses, and danger to their feet, while the noise 

 produced by their grinding together is annoying to the inhabit- 

 ants. Upon tlie improved method, the inconveniences of road 

 repair are incomparably less than those of pavement: both re- 

 coating and repairs may be made without stopping the traffic. 



Under no circumstances must any imperfection of surface be 

 allowed, — if a hollow be not immediately stopped it very quickly 

 extends over the surface; and all loose stones carefully picked, as 

 every loose stone passed over by heavily-laden carriages, if not 

 ground to powder, breaks the crust of the road; and if water be 

 permitted to lodge on the surface, it will cause great mischief. It 

 is the neglect of these essential precautions that has led many to 

 consider macadamised roads very expensive: they are expensive if 

 neglected. On a well-made road heavy showers do good, by 

 cleansing them; so also does artificial watering, if the road be 

 clean or swept quickly after it is watered. A road which is per- 

 fectly dry loses its tenacity and the surface grinds into dust; 

 whence the economy of judicious watering in hot weather, which 

 preserves the road as well as prevents the annoyance of dust. 

 The practice so common in London and elsewhere, of heavy wa- 

 tering a dirty road without cleansing it, is very injurious to the 

 road, and merely changes one nuisance into another — dust into 

 mud. 



A great source of waste both to those who use and those who 

 repair a road, is to allow it to be dirty. The draught upon a dirty 

 road is twice as hea\y as on a clean one — that is, a horse must 

 exert double force to draw his load with the same speed. The 

 cost, however, of employing double force is so great that the ex- 

 pedient of diminishing the speed is generally adopted, as a horse 

 can exert greater pulling force at a slower pace, less power being 

 required to carry his own body. It often happens that the extra 

 resistance occasioned by dirt diminishes the speed one-fifth or one- 

 fourth. The effect of the dirt, therefore, is to increase the work 

 by 20 or 25 per cent. It will easily be believed that such a waste 

 far exceeds the cost of the most perfect cleansing. This is the 

 case when cleansing is done by scrapers (the greatest enemy a 

 macadamised road has to contend against); by their use the stones 

 are dragged from their places, and the adhesive dirt is not effec- 

 tually taken away. Sweeping is the only mode of cleansing that 

 should be allowed either on streets or turnpike roads. Sweeping 

 by the wide brooms of the machine is preferable to all other modes 

 of cleansing yet tried. 



It must be evident that these wide brooms, sweeping longitudi- 

 nally, with a pressure that can be adjusted according to circum- 

 stances, tends powerfully to preserve the road, and to consolidate 

 its surface: they press most upon the ridges, and least upon the 

 ludlows, thus tending to reduce the former and fill up the latter. 

 When the dirt is stiff, and adheres firmly to the stones, it should 

 first be well watered, when it may be completely removed by the 

 machine without disturbing the crust, leaving the surface firm and 

 com])act. The use of water for this purpose has been objected to 

 by high authorities, on the ground that it does remove the useful 

 grit: but the contrary has been proved by ample experience. 



I have found that the use of the sweeping-machines, with the 

 proper employment of water, has reduced the amount of material 

 required for the repair of roads in Birmingham, one-third — viz., 

 from about 20,000 to 13,000 cubic yards. The first-named amount 

 is the average for seven years preceding the introduction of the 

 macliines; the latter, of the three years subsequent. 



Tlie entii-e cost of cleansing and watering Birmingham is about 

 5,000/. per ainium, or less than one penny per week for each of its 

 inhabitants. 



8. On the Manufacture of the Finer Irons and Steels, as applied to 

 Gun Barrels, Swords, and liailway Aaks. By Mr. W. Gkeeneb, of 

 Birmingham. 



No manufacture has tended more to advance the improvement 

 of the finer qualities of irons than that of gun-barrels, which has 



Eroceeded from the old stub-twist barrel of former days to the 

 iminated steel of the present time, and has been attended with 

 the advantages of increased security and greater projectile power 

 of the gun. It might be naturally inquired why the principle, if 

 so advantageous, has not been applied to other manufactures where 

 even greater security to life and limb is required than in a gun- 

 barrel. The first innovation on the old principle of manufacturing 

 gun-barrels, or tliat of making them entirely from old horse-nail 



