Some of our readers will be much interested in the simple but valuable improvement illustrated in the accompanying engravings. Many of them have been annofed by glasses coming out of the frames, and have been sorely tothered in the absence of proper implements to replace them. In the case of spectacles with spring frames, should the spring chance to break, it is difficult for people under ordinary circumstances to repair them, and much annoyance often results from the loss of time necessary in sending them to a j eweler. The present device obviates all these annoyances, and will add greatly to the comfort and convenience of those who are obliged to assist their eyes by the 11se of glasses. Figs. 1 and 2 show the improvement as applied to the. old style of spectacles; Fig. 1 exhibits the rim which holds the glass closed, and Fig. 2 the same unclasped for the insertion of a glass. Where the two ends of the rim meet, Fig. 2, one is grooved to receive a slight rib upon the other which fits into it. A clasp, A, which plays fy.L Ity.Z. upon the same pivot as that upon which the side bows play, when closed over the end of . the rim, B, holds it in place far more securely than the old screw, and may be opened or closed with the utmost facility. A perSon purchasing spectacles withthismethod of putting in the glasses, may provide himself with an extra glass or two, and at once replace a broken one for himself, or by sending the number to the makers he may obtain a glass to correspond and insert it himself without the slightest trouble. Fur. 3 Fig. 3 shows an improved method of attaching the springs to eye glasses. A small metallic clasp, C, is riveted to the rim. To this clasp is pivoted a small lever eccentric, D. This lever eccentric, when opened into the position shown © 1869 SCIENTIFIC AMERICAN, INC by the dotted lines, releases the spring, E, which is not pierced for rivets, as such springs have hitherto been. When the eccentric is closed it holds the spring securely, and the liability of the spring to break at the point where it is riveted in the form heretofore employed is obviated, the spring being as strong in one place as another. Should it break, however, at the point of j unction, the eccentric may be opened by the thumb nail, the end of the spring reinserted, and the glasses can then again be used, the only inconvenience being a slight shortening of the spring, scarcely perceptible to the wearer. Fig. 4 is an application of the samef principle to another form of frames for spring glasses, the level' eccentric being || in this case. identical with the piece formed to rest against the side of the nose. The manner in which the spring' is clasped is sufficiently well shown to render description unnecessary ; the dotted outline showing the position of the lever eccentric when open ; this eccentric when closed being held from opening by a small metallic button, F. The advantages claimed for this improvement, and which we are satisfied are fully attained, are very much greater convenience to the wearer, the ready insertion and in- terchangeability of glasses,great61 strength, without any decrease in grace and lightness, as the addition of the clasp gives scope • for ornament rather than othei wise, and the easy replacing of' the glasses, or the springs when broken, without tools. We have been much pleased with this improvement, and the inventor informs ub that it is intended to make standard size glasses, so that glasses may be sent by mail to replace such as may be broken, all the required information being the number of the glass to be replaced. This will prove a great convenience to those at a distance, and will save much trouble. Jewelers and others who keep spectacles for sale will also find this farm of bows a great convenience, as, when a peculiar style of frame pleases aand the glasses are not right, an interchange of glasses is but the work of a few seconds, which may be done as well at the show case as the work bench. ' Patented through Scientific American Patent Agency, Oct 19, 1869. •For further information, address the pat entees, L°uis Black&Co., Detroit, Mich. Coal and Coal Mines. Dr. Hill, of Queen's ' College, Birmingham, England, in a recent lectureon the"Chemistry of the Mine,” made some interesting remarks' on coal and co al mines. He said: ” The history of thesewas mOst interesting. Their age must be veryhave never been found with any traces of human. remains. The principal animal forms were of a much lower type, consisting of snails, fish, reptiles, and insects. The impressions they have left, and the skeletons of them which remain, show that they were of a similar character to what are now known as” horsetails” pines, resembling th e Arancaria of gardens, ferns, club mosses and a sort of palin. These were all of great size, the ferns branching to a hight of 50 feet ; and the club mosses, now insignificant, were then 60 or 70 feet high. Taking into con sideration the gigantic dimensions of the different plants, and the branched character ofthe ferns—such as only grow in hot climates—led them to conclude that England must at one time have had a tropical climate. A period when such rapidly growing and enormous plants of unlimited number existed is thus seen to have been highly favorable to the formation of those immense stores of vegetable matter—which may have been like peat beds, or carried on by river currents to their present beds—forming coal . There was no doubt but that coal was changed wood, such change being due to moisture, heat and pressure. They might look upon wood as carbon, hydrogen, and oxygen. As soon as a plant died it began to decay, and then the three elements ente;red into new combinations to form compounds which did not exist in the original wood. One part of the carboD entered into combination with part of the oxygen to form carbonic acid ; another part combined with some of the 'hydrogen to form carbureted hydrogen, or “ fire-damp;” while the remaining carbon, having no more oxygen or hydrogen to combine with, remains and constitutes black coal. If' there were enough oxygen. THE Crown Prince of Prussia is said to have invented in new apparatus for the manufacture of vinegar.