1818.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



283 



the mile, and on (his contour lines at four feet altitudes have been laid 

 dowa. Tliese contours involved the observation of a great many levels, 

 and a laborious calculation. A copy of this has Ijeeu made for Mr. 

 Hawkesly, for the purposes of the water supply. 



Besides this work, belonging especially to ihe survey required by the 

 Act, a very great number of detached surveys and the sections, to meet the 

 emergencies of the time, working drawings of sewers, and of the new 

 ottices in C'ornwallis street, and many highly-finished drawings to illustrate 

 the reports made by nie, have been executed by the surveyors and 

 draughtsmen; and although these are, for the most part, valuable docu- 

 ments, their execution has not a litile interfered wiih the progress of the 

 larger work. The street surveys and sections required for the adjustment 

 of the levels in laying out new streets alone amount to 150. 



The work being now so far advanced, and the completion of the contour 

 plan having enabled me to make the necessary estimates of the cost of ihe 

 sewerage, a reduction may be made in Ihe surveying stuff, if it should be 

 thought desirable. The list of the new stafl' I have sulmiitted in the 

 estimate of the expenses of the Engineer's Department for the ensuing 

 year. 



FROCSEDINGS OF SCIENTIFIC SOCISTISS. 



INSTITUTION OF MECHANICAL ENGINEERS. 



The following papers were read at the last monthly meeting held at 

 Birmingham : — 



BONE CRUSHING MACHINE. 



Mr. Buckle premised that, in selecting his present subject, he had had 

 in view the desirability of imparting an agreeable variety to their proceed, 

 ings. The object of this communication was to endeavour to direct ih- 

 attention of agriculturists to the usefulness of a machine for preparine 

 bone dust, which has been found to be a most efliciicious manure, g 

 machine which is alike available to renovate the nobleman's estate or tha 

 peasant's cottage-garden. An ash plant, an iron bar, a pebble from the brooke 

 and a hand sieve, furnish him wiih a bone-mill for all he requires. The ar- 

 rangement of this machine reduces bone to a state of meal, and thereby 

 prepares it for a rapid change into a state of solubility — the rapidity of the 

 effects of phosphate of lime on the growth of plants depending upon its 

 greater or less solubility. In all other mills which he had examined, their 

 construction will merely crush the bones into lumps ; and when laid on the 

 land in that state they remain many years undecumposed, with little benefit 

 to the crops. 



In the year 1833 his attention was directed to this subject by the stew- 

 ard of a large estate in Oxfordshire requesting hi]n to construct a mill to 

 grind bones as fine as possible ; for he found, in practice, that the bones 

 prepared in the usual manner were of little benelit: he also objected to 

 the usual method of boiling the bones before they were crushed by the 

 rollers. For this gentleman he constructed a mill driven by two horses, 

 which succeeded so well that he was requested to increase its powers, and 

 to work it by a water-wheel of three-horse power. The first crop of 

 turnips averaged 47 inches in circumference and 32.J lb. weight, 

 from seed of the red turnip, received from Messrs. Drummond and Son, 

 Agricultural Museum, Stirling; sown in May, and producing as above in 

 October. In the year 1839 he constructed a second bone-mill, which was 

 erected on an estate in Surrey, driven by a water-wheel thirteen feet in 

 diameter and four feet wide, with additional conveniences to the former 

 one. After a careful course of experiments, he received a letter from the 

 proprietor of Ihe estate, of which the following is an extract : — " I am 

 much obliged by all the attention you have given to my bune-mill, with the 

 performance of which I am entirely satisfied. We produce thirteen 

 bushels of fine dust per hour, and seventeen bushels of fine dust appear to 

 be the product of half a ton of raw bones. Thus we shall be able to pro- 

 duce 136 bushels of dust, the product of four tons of raw bones, per day 

 of ten hours." In the sketch of a mill or machine laid before the meeting, 

 Mr. Buckle made several additions and improvements which were not in- 

 troduced in Ihe former ones. The positions of the stampers were altered 

 in consequence of the result of experiments, and elevators were an 

 addition of much usefulness, as he thereby lessened the duties of the at- 

 tendant, whose only care is to admit water on the wheel, and observe that 

 the store of rough raw bones is ample, and the machine performing satis- 

 factorily. The rough bones are recommended to be heaped up in a shed 

 adjoining the mill ; they are permitted to slide down the inclined platform, 

 from whence they drop into the stamper-trough. The middle stamper is 

 recommended to be heavier than the outside ones, lo enable it to break the 

 large bones in pieces ; those pieces pass on in the trough from one stamper 

 to the next, and when it has moved to the outside stamper it is reduced 

 into meal. It then passes into the dressing cylinders, which are placed on a 

 descent, and by their velocity force the fine dust through the wires. The 

 coarse dust falls from the end of the cylinders into a box, where it is raised 

 by the elevators, and descends into the stamper-trough, to be crushed fine 

 enough to pass through the wire meshes of the dressing machine. Mr, 

 Buckle also recommended the application of elevators for conducting the 

 ground bone dust from the bins or store in the cellar into the wagons, to be 

 by them conveyed to the drill or sowing machines. 



HIGH-PRESSURE BOILERS. 

 " On High-Pressure Boilers, and on Boiler Explvsions." By Mr. 

 Smith. — "At the last meeting I laid before you a tracing and description of 

 the steam-boiler which recently exploded near Dudley, and though time did 

 not permit any discussion as to the merits or demerits of the construction 

 of the said boiler, I think it very evident that boilers of similar construc- 

 tion, formation, and dimensions, cannot be safely used for high-piessure 

 steam, say 40 lb. or 50 lb. per square inch. I make this assertion, because 

 the great diameter of the outer shell renders it very liable to be torn 

 asunder by the internal pressure, and the internal vertical-flue being also 

 of such dimensions that it may be forced out of form and suddenly col- 

 lapsed by external pressure, and if that system of boiler were to be made 

 safe by a large reduction of the diameter, it would make steam insignifi- 

 cant in capacity, heating surface, and generating power, and consequently 

 unfit for the purpose they are intended — namely, to use the great quantity 

 of lost heat that escapes from the puddling furnaces. 



" I have prepared the accompanymg drawing of a boiler which I recom- 

 mend in preference to those on the above principle, being much belter 

 adapted for generating and safely containing high-pressure steam, and I 

 think more convenient in every other respect tor the above system ot 

 heating. The boiler is 32 feet long, and 4 ft. in. diameter, with two 

 tubes or flue-pipes under if, each 30 feet long, and 1 ft. 8 in. diameter, and 

 attached to the boiler by vertical pipes 10 inches diameter. The llue-pipes 

 are made in a bent form, so as to be highest iu the middle, and droppinij 

 at each end, to keep circulation in the water. The drawing willsudi- 

 ciently explain every other particular connected with this boiler, so that 

 further description is unnecessary; I shall therefore now ouly point out a 

 few of the advantages it possesses over the system of boiler before re- 

 ferred to ; — 



" 1st. The diameter of this cylinder being small, they may be made of 

 much thinner plates, and still be perfectly safe with a greater pressure of 

 steam. — 2nd. The heating surface is large, and concentrated without 

 winding flues, so that much steam will be generated. — 3rd. The area of 

 water surface being much larger, there will be less difliculty in maintain- 

 ing its proper level. — 4th. The steam and water spaces and heating sur- 

 faces harmonise iu their proportions. — 5th. The great facility for cleaning 

 out, which is an object of the first importance in the construction of all 

 kinds of steam-boilers, as it is weM known that where any difliculty exists 

 in performing that operation, the chances are that it will either bo imper- 

 fectly done or left undone altogether, which is one cause of many of the 

 fatal explosions that so frequently happen with land boilers : — I, 

 Mal-formation for the working pressure and quantity of vapour re- 

 quired ; 2, Want of proper care lo fit every boiler with proper steam 

 and water indicators ; and 3, Neglect of cleaning out at proper times. It 

 is a lamentable fact that many boilers are still in use, which are extremely 

 liable to accident from either of the above-named causes ; and I think the 

 following reasons will to a great extent account for so bad a state of things 

 existing in a country where so much engineering skill may always be pro- 

 cured to rectify such defects. 



" I. Respecting mal-formation, I would state that parties about making 

 erections for steam-power, generally make the first outlay of capital a 

 leading consideration, and consequently cramp the dimensions of their 

 engines so that they are just calculated to do the work required, and 

 nothing lo spare. Shortly afterwards, however, some extra machinery is 

 introduced into the establishment, and the engine being found defective in 

 power with Ihe original pressure, an extra load is immediately put upoQ 

 the safety-valves of Ihe boilers, and this praciice is repealed from time to 

 time, as each little additional machine may require Ihe extra power. It 

 follows that the boilers, which were prudently arranged to do the work iu 

 the first instance, are at last a mal-formation for Ihe increased pressure, 

 and working in a highly dangerous state, while the unsuspecting opera- 

 tives may be seen crowding round to warm themselves at meal times, 

 when the danger is probably at the greatest pitch. 



" II. Respecting defective steam and water indicators, I have always 

 observed that land engine boilers are not so efficiently fitted with these in- 

 struments of safety as marine and locomotive boilers, although I think it 

 very necessary that they should be so, seeing that a number of Ihem are 

 frequently left to the charge of one individual, with other duties besides 

 that require much of his time and attention ; whereas the indicators of 

 marine and locomotive boilers are constantly under the eyes of one or 

 more engineers of well-proved character and ability for the duties re- 

 quired ; and, moreover, engineers of a higlier class are always resident ia 

 ilie principal stations, invested with power to examine engineers, and 

 inspect the whole machinery. I have shown, on the present drawing, all 

 the indicators which 1 consider necessary for a high-pressure boiler in 

 ordinary circumstances, v»hich are as follows:— One feed-cock or valve ; 

 one float-water gauge, with stand and wheel, and counterbalance weight; 

 one glass water gauge; one steam-whistle, also for a water gauge; and 

 two safety-valves, one locked up. For low-pressure boilers, I think the 

 open top feed-pipe, with open pipe also for the float-wire to work through, 

 is a very perfect apparatus to prevent the steam from rising too high, or 

 the water getting too low. 



3rd. Respecting keeping of boilers clean, I have seen that process very 

 imperfectly performed, and often altogeiher neglected in establishmenis 

 where a sulhcient number of spare boilers are not provided, aiid time not 

 permitting to get the boiler cooled down for men to remain in it to do the 

 work properly. But 1 believe the greatest cause of neglect in this most 



37* 



