230 



NEW ENGLAND FARMER. 



cent of smoke up the chimney depends on tlie com- 

 parative lightness of the cohimn of air within to 

 that of an equal column without, the longer ihe 

 chimney the stronger will be the draught, if the 

 fire be sufficiently great to heat air; but if the 

 chimney i)e so long that the air is cooled as it ap- 

 proaches the top, the draught is diminished. A 

 case of this kind occurred at a lighthouse on the 

 Isle of Portland. The chimney which ventilated 

 the building and the lantern was carried on the 

 outside, and in the winter time the draught was so 

 much impared that the windows became dim and 

 the lights obscure. An attempt had previously 

 been made to remedy the defect by lengthening the 

 chimney; but that, of course, had made it smoke 

 all the more. The application of a jet of steam to 

 increase the blast of locomotive engine furnaces was 

 illustrated. The lower end of a bent glass tube 

 was placed in a dish which contained colored li- 

 quid, the upper end being inverted into a larger and 

 horizontal tube. A jet of high pressure steam di- 

 rected through the larger tube caused such a rusii 

 of air to supply the place of the aii expelled by the 

 steam, that the colored liquid rose to the top of the 

 tube. The mechanical force of a jet of high pres- 

 sure steam was shown by causing it to sustain an 

 egg, which was seen dancing about in the air with- 

 out anything apparent to support it. — Scientific 

 American. 



RSSTORATION OF SIGHT. 



Mr. J. Ball, of New York, has lately patented 

 an instrument for the i-estoration of sight to aged 

 persons, which promises to be very useful in rem- 

 edying one of the most trying ills of old age. The 

 instrument, — of which we give an engraving above, 

 — is very simple, consisting merely of a hollow 

 India rubber ball, a, attached to a cup, b, which 

 fits on the eye. The air is first partially expelled 

 from the ball by pressure between the fingers, be- 

 fore the cup is applied to the eye. On removing 

 the pressure the ball distends and a partial vacuum 

 in produced, drawing on the eye and tending to re- 

 store its convexity. The pressure is regulated 

 according to pleasure. Prof. Bronson, and other 

 eminent occulists, accomplish the same result by 

 manipulation, but probably not so efficiently. The 

 price of the instrument is $2,.50. 



The following is the explanation of the inventor: 



"The cause of the decline of sight is the flatten- 

 ing of the lens or cornea of the eye; and the object 

 of this instrument is to restore the convexity if lost, 

 and to preserve it if first beginning to decline. 

 Having tried the effect upon myself, I can speak 

 with confidence, for from having been unable for 

 the last six years to read or discern the form of any 

 letter, I can now, after a trial of six months, read 

 without the aid of glasses. This is effected by a 

 simple instrument, made upon philosophical prin- 

 ciples, by which the cornea of the eye is gradually 

 raised to its original convexity, causing the focus 

 to impinge upon tiie retina without the aid of con- 

 vex lens; and will be accomplished ten-fold more 

 rapidly than the sight declined. The application 

 will be made once or twice a week with less trou- 

 ble than that of shaving, and no loss of time, as it 

 is most conveniently applied after retiring to bed." 



ON FITTING HORSE-SHOES HOT. 



The following is from a review of the Bulletin 

 of the Central Society of Veterinary Medicine, pub- 

 lished under the direction of its committee, and the 

 editorship of M. H. Bouley, the Annual Secretary 

 — in the London "Veterinarian:" — 



Although hot shoeing has had some enemies in 

 our country we know of but few advocates for the 

 cold plan. M. Delafond, the author of the paper 

 before us, concurs with the committee in the rejec- 

 tion of the 'podometre or foot-measurer, the inven- 

 tion of M. Riquet, and proceeds to inquire if there 

 is any serious or real objection to fitting shoes hot 

 to the feet. 



Fitting shoes hot — hot shoeing as it may be called 

 — is said to heat or burn the sole, to dry the hoof, 

 to incline its fibres to separate, to incite inflammation 

 in the internal tissues of the foot, and to produce or- 

 ganic alterations in them of a grave and hardly re- 

 mediable character. It was not until the middle of 

 the eighteenth century that hot shoeing came into 

 practice, and the first author we find complaining 

 about it is Lafosse, who, in his "Nouville Pratique 

 de Ferrer les Chevaux," 3d edition, published in 

 1758, has spoken of such accidents under the names 

 of heated and burned hoofs. And his son (Lafosse, 

 jun.,) has well described them in his "Guide du 

 Marechal," and subsequent works. 



If burning the hoof is an evil consequent upon 

 hot shoeing, is it a frequent occurrence ■? The com- 

 mittee and M. Reynal have already come to the 

 conclusion that it is not, and I am quite of their 

 opinion. In order, however, to assure myself fur- 

 ther than the mere on dit practice of the forge on 

 this point, I resolved to institute a series of experi- 

 ments on the conducting power of horn of caloric; 

 and the results have proved as follows: 



1. That the conducting power of the crust is in- 

 ferior to that of the sole; whence we derive the in- 

 dication in practice, -that it is absolutely essential that 

 the heated shoe should not be allowed to come in 

 contact with any substance but the crust. 



2. That caloric is transmitted tardily either 

 through crust or .sole. 



3. That it is not before the elapse of three, four, 

 or five minutes after combustion that the thermo- 

 meter indicates the highest decree of heat in the 

 hoof. 



4. That the thinner the horn of the crust is the 



