THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[January, 



has been found in prai'tico ti) ansni'r well ; that is, the space be- 

 tween tlie fan and the chest should increase, fnini i| iif an inch at 

 the ti>p (if the inlet to the transit Jiipe, to ,', of tlie diameter of the 

 fan at the bottom of a line perpendicular with the centre. The 

 tunnel, or main pipe, from the fan chest may for short distances, 



varyinif from 50 to 100 feet in length, be made not less than 1^ 

 times the area of the transit jiipe in the fan chest ; aiul in distances 

 varying from 100 to 200 feet in length, U times the area of the 

 transit pipe. The length of a tunnel maybe continued to 300 or 

 more feet, provided it be made (jf sufficient dimensions to allow the 

 air to pass freely ahjug it. The experiments accompanying this 

 paper were made with ;>. tunnel 18 inches diameter and 160 feet in 

 length, and no difference could be detected in the density of the 

 air, wlien the gage was ap])lied at any part of the tunnel. 



Having investigated the leading characteristics of the fan, it may 

 not be out of place to give a few hints respecting its mechanical 

 construction. 



Fiivt. — It is one of the greatest essentials, that all parts main- 

 tain a just and ])ro|>er balance. 



Second. — That the arms of the fan be as light as is consistent 

 with safety: round arms are decidedly objectionable ; I have known 

 instances when their centrifugal force has torn them from the cen- 

 tre boss. I prefer the rectangular arm, about the pro])ortion of 2^ 

 times the width, for the depth at the centre, with sufficient taper 

 towards the tips. 



r/i»r/.— The bearings and journals of the fan spindle should be 

 made of a length not less than four times the diameter of the necks 

 of the spindle. 



Finiil/y. — The driving pulleys should be made as large as circum- 

 stances will admit of, so that the strap may have sufficient surface 

 to prevent slipping. 



The fan from which my experiments were collected, was made 

 with these proportions. It has been at work nine years without 

 any perceptible wear. 



The apiilication of the fan has hitherto been chiefly applied to 

 smithies and foundries ; and in but few instances has it been ap- 

 plied to the smelting of iron ore. I am aware that differences of 

 opinion exist as to the applicability of the fan to that purpose. The 

 principal reason urged against it beinif the limited density to which 

 the blast can thereby be compressed, compared with the blast sup- 



plied by the cylinder. It remains, however, to be proved whether 

 such high densities are absolutely necessary for the smelting of 

 iron ore; whether we may not produce as good iron by a diffused 

 soft blast, as by the strong, and generally apj)lied, concentrated 

 blast. I hojie it will not be thought presumptuous on my part, in 

 thus doubting long established practices. The old maxim of 

 " there's no way like the old way," is not always based on unerring 

 jnunciples. 



As I have before stated, the density of blast afforded by the fan, 

 is limited to the force arising from the centrifugal motion of the 

 air, in passing along the vanes of the fan ; the quantity not ex- 

 ceeding what is due to its velocity and magnitude. But may not 

 this density be increased by using a succession of fans, so con- 

 structed and arranged, that the air may be passed successively 

 through each ; the air from the first fan being made to enter the 

 seccuid , the air from the second to enter the third ; and the bUust 

 finally emitted of ade(piate density .'' 



I cannot here enter into a further investigation of this important 

 subject ; neither are the limits and character of this paper suite*! 

 to the miuutiie connected with the principles and practice of a 

 smelting furnace ; but 1 ho))e that the observations which I have 

 made, and the principles I have endeavoured to enunciate, wiU be 

 the means of instituting further inquiry ; and, as the expense of 

 constructing a fan can be no barrier, I trust that a fair trial will 

 he made, where convenience is suited to its application for smelt- 

 ing purposes. 



REGISTER OF NETV PATENTS. 



VENTILATION OF MINES. 



John Wilcock, gentleman, in the county of York, for " cer- 

 tain Improvements in the ventilation of mine.i." — Granted June 12 ; 

 Enrolled Dec. 12, 184.7. [Reported in the Patent Journal.'^ 



The patentee, in this specification, states his invention to be for 

 the purpose of improving, and more effectually securing, the better 

 ventilation of mines, and consists of elongating the upcast sliaft of 

 the mine, by the addition of stacks, towers, or other similar build- 

 ings, erected above, or in connection with such upcast shaft, by 

 which the upper orifice of the upcast shaft is elevated very consi- 

 derably above the upper orifice of the downcast shaft, proportion- 

 ably to various circumstances — as the relative depths of the two 

 shafts, the velocity of the .current of air through the mine, the 

 nature of the gases, &c. The ventilation of mines is effected by 

 the passing of a stream, or current, of atmospheric air through 

 the various ramifications of the mine, carrying with it, in its 

 course, the various noxious gases — as carburetted hydrogen, car- 

 bonic acid, and also the vitiated air, in its course, and escapes 

 through the upcast shaft into the atmosphere. This current is, in 

 most cases, caused— or the velocity of it is increased— by the ap- 

 plication of heat to the upcast shaft, either at the bottom thereof, 

 or at the orifice at the surface. The patentee proposes, by his in- 

 vention, to increase the velocity of the currents through the up- 

 cast shaft, by erecting a stack, tower, or other similar building, 

 above, or in connection with, the upcast shaft, which forms a con- 

 tinuation of the shaft, and through which also continues to flow 

 the current of air. The height to \vhicli, in most cases, it will be 

 sufficient to raise the elongated portion of the shaft, the patentee 

 states to be from 60 feet to 100 feet, though this will be go^•erned 

 much by circumstances, varying in difl'erent mines. The patentee 

 gives several drawings, descriptive of his invention, as applied to 

 se\eral descriptions of mine shafts ; as, first, to its application to 

 mines having only one shaft ; in this case, it is customary to make 

 partitions down the shaft, thus forming downcast and upcast shafts. 

 The patentee proposes leaving these arrangements as usual, but 

 erecting over, or in connection with, the part of the shaft, a stack, 

 tower, or other building, as a continuation of the upcast shaft. 

 Secondly, to a mine in which the upcast shaft is also the working 

 one; in" this case, the minerals and workmen pass out of the lower 

 ])art of the stack, or tower, by an aperture in the wall of it ; and, 

 thirdly, to a mine in which the upcast shaft is only employed for 

 that purpose ; in this case, a plain stack, or tower, is employed. 

 In all cases, the patentee states, it is necessary that the sectional 

 area of the stack, or tower, should be, at least, equal to the sec- 

 tional area of the upcast shaft ; and that, when it is necessary to 

 have any openings into the lower part of the stack, or tower, the 

 sectional area of the upper part of the stack, or tower, above the 



