Conecting lead with lead, by running a stream of very hot liquid lead, suitably confined, in contact with a surface of solid and cold lead, until the latter had got to its melting point, and then stopping the currcnt, so that the two portions become united when both are solid, has been k'nown to plumbers for ages under the name of “burning together.” In fact, by this method some of the earliest lead water pipes were made before drawn pipe was known. Ts same method of “burning together” may be also employed by the iron founder, and occasionally with great ad' vantage. The writer, in the course of his early practice, had occasion to cast four of the very ponderous columnar cast-iron frames which, in the earlier days of steam navigation, were to be employed for the side frames of side-lever marine engines of the heaviest class. The frames in question consisted of coupled Roman-Doric columns of considerable diameter, cored out, with cross framing and entablatures, also all cored out, and with sundry proj ecting pieces like truncated horns. etc., whereby the frames were to be united with other “thwart- ship” pieces, each frame weighing several tuns and consuming a large amount of wages in molding. All four were cast sound and without a blemish, except that, upon the top box in which one of these was castall being cast in green sandsome one had unluckily dropped a bar or something heavy, or put a foot upon it, and produced “a crush,” which rendered one of these horns utterly amorphous. The casting, otherwise perfect, was in that state absolutely useless, and was about to be broken up, when the writer resolved to try and save it by attempting to “burn on” a new and perfect horn. The old and defective mass was care- fujly cut off, and removed down to absolutely sound metal. “ Loam cakes,” having the proper form for the horn,were taken from the pattern,the surface of the cut metal was well dusted over with powdered glass of borax, after that the mass of the “ frame,” in close propinquity with the defective place, had been heated red hot in a coke fire built up around it. The fire was then raked away, the loam cakes secured in place, and several hundred weights of very hot liquid cast iron were for some time kept flowing through the cavity of the loam cake hollow mold. At length the fiow was stopped, when the cut surface could be felt, with the point of an iron bar pushed through the running metal, to have become pasty and soft, and the iron was then permitted to set. When finally stripped and” gates” etc., removed, the new horn was found to be perfectly united with the remainder of the casting, and when struck it gave the clear sonorous ring which proves complete metallic continuity. The success, in lact, was perfect, and somewhat surprised both the writer, to whom so large an instance was new, and the marine engineer responsible for the supervision of the work, who would not pass the casting until he had assured himself of the safety of the horn by striking it heavily with a sledge hammer. This method is capable of being applied not unfrequently with similar ends in view, and may often save the condemnation of a casting and effect a good deal of economy. It can almost always be made effective, if the methods be judicious, for attaching, as in the above case, a heavy piece to a heavy casting; but it is a far more delicate and difficult task to make it succeed with smaller and more delicate work, and there are two generic cases in which it is useless to attempt it. One of these is where the form or dimensions, or both, of the casting must remain precisely the same after the work as before ; as, for example, if a piece be defective in the rim or in one of the arms of a large spur or head gear wheel, there would be no great difficulty in replacing it soundly by casting together as described ; but either the wheel would crack somewhere on the setting of the “burnt-in” metal, or during its cooling, or it would have lost its circular form and"truth” when all should be cold. x Again, if the mass of casting be very great, and it is but a hole or cavity,regular or not, that requires to be filled in with metal, which must be perfectly united with the remainder, this can scarcely be accomplished unless at an expense that renders the process worthless ; for lhe whole huge mass must be brought to a strong red heat, with great expenditure of fuel and time and surface injury to it by oxidation, or the union will prove imperfect. Such has been the fate which has al ways attended attempts thus to restore defectively cast cylinders for hydraulic “presses. The writer,however,has little doubt but that a sort of small coke-fed furnace, with a strong blast, delivering from a small brick-lined mouth a jet of fiame like like that of a large blow pipe, might be so used as to heat even up to the melting pointand but very locally or partiallyany mass of cast iron however huge, so as to admit of” burning on “ to it. He once witnessed sufficient proof of this in the method taken to repair a defect which appeared in the neck of a very heavy cranked intermediate shaftdfor marine engines, at the Thames Iron Works, just before MI'. Mare ceased to direct them. The neck of the crank about eighteen inches in diameter, was rough turned, when a hole was found and cut into in the forging, close to the angle of the neck where joining with the arm or side of tiie cranked part. Nothing could be more awkward as to position, and the condemnation of the whole forging, and serious loss, seemed imminent. The foreman blacksmith determined upon one trial to save it. He got up just such a coke-fed giant blowpipe as has been described, and drove its flame right into the defect or cavity, having carefully “ clayed up “ the iron of t.ie rest of the crank adjacent, to save it from oxidation. In about five hours he had the interior o1 the cavity at a fine uniform and clear welding heat. A piece of wrought iron, well judgedas to form-to rather more than fill it, had been got ready, and at the right moment was brought, in a forge fire, to a welding heat also; and the blowpipe blast being thrown off, the welding hot plug, preceded by a dust of sand and borax glass, was thrust against the cavity, and a single blow of a” tup,” beforehand properly swung ready, sufficed to firmly weld it into place. The superfluity, when cold, was chipped off, and the turning of the neck completed, which the writer witnessed; and h'il can testify that it was not possible upon the clean cut surface then to discern where was the new iron, and whore the surrounding old of the original forging. The work refiected much credit upon the skill of those who conducted it, and in that respect alone deserves to be recorded. The method of heating, however, is quite as applicable to cast as to wrought The marine-engine framing above referred to was treated about 1883. In the “ Annales des Mines “ for 1860, M. Mengy gives a circumstantial account of the same method having been applied about the same date at the Tamaris Iron Works, Department of Alais, to “ burning on “ the broken-offnecks of thtron rolls of the rolling mill, and with complete success. Dr. Percy (” Metallurgy,” p. 745) states that he has seen a roll thus repaired at the Millwall Iron Works, and that the method has been in occasional use elsewhere. THE State fairs in progress throughout the country have generally been very successful. Thirty thousand people visited the fair grounds at Elmira in one day Home-Made Ladders. In inaking ladders, says the American AyricuIturist, we prefer to use rod cedar for the poles, and oak for the rounds. White cedar will answer well, and so will white pine or spruce for poles, and the rounds may be made of many different, woods. Dogwood is good, cutting stems of the right size, and the bark may be left on. Hickory does well, if the ladder be kept painted, and not exposed to the weatherotherwise it rots at the ends where inserted in the poles. Cut a straight cedar pole of at least six or eight inches in diameter at the butt, and of the desired length, if such a one can be found. Lay up to season six months or a year, and take care that in drying it does not get a bend. With a little painstaking it may be improved in straightness while seasoning, if not straight. Then shave off the bark and branches with a drawing-knife; cut it of the right length; plane down a strip of three inches wide on opposite siies, and mark it and saw it in two in the middle lengthways. If well done, we shall have two long, straight, sound, tough, stiff poles. Mark off the points for holes for the rounds alike in each ; fourteen inches is a good distance to have the rounds apart. If the ladder is to be a wide one, the lower rounds should be an inch and a quarter in diameter, and the holes an inch, while the upper rounds need not be more than an inch in diameter. For a ladder fourteen inches between the poles, inch rounds are large enough for the bottom ones, and five eighths inch for the top. Split and shaved rounds are as good as turned ones, unless one is making a very nice job, when the rounds may be split out and then turned. It is well to make the rounds with a slight shoulder, so that the poles cannot be driven together at all by a fall. This is apt to split them, and if the rounds are simply shaved down to enter the holes, it is imperatively necessary to insert several flat rounds tWo or two and ,t half inches wide and three quarters of an inch thick, having tenons at the end, with strong shoulders, and fitting into mortices. When the ladder is put together, dip the ends of tho rounds in paint; set all the rounds in one pole first, then put on the other; and, finally, after sawing off the ends of the rounds, drive hard-wood wedges into each alternate round, so as to spread the ends and prevent their drawing out. Wedge the fiat ones particularly. With a plane, a drawing knife, and a little sandpaper, the ladder is easily finished, and a good coat of varnish will make it last a long time as good as new. The Volcanoes of Cotopaxi and CMmborazo. In January, 1802, Humboldt and his friend Bonpland, reach ed Quito, and attempted the ascent of the grandest peaks of the Cordilleras but they were defeated by the difficulties of the enterprise. In the eruption of 1739, Cotopaxi vomited red-hot stones 3,000 feet above the crater, and its roaring was heard at a distance of two hundred miles. It is the most terrible volcano in the whole range ; its form is a perfect cone, crowned with snow, and its appearance is eminently grand and beautiful. In the attempted ascent of Chimborazo, the explorers were accompanied by a young Spaniard. They started from the south west side, traversing great plain8, which rose one 'above the other, like terraces, until they reached that of Sisgun, 12,400 feet above tlie level of the sea. They continued to ascend until they reached Yava-Cocha, a circular lake, the highest spot yet reached by other travelers. Here they left their mules, and crossing a plain of tawny grass, they came to a region where the rocks rose in columns, like an enchanted forest of stone. Passing over this district, they arrived at a place where the path became too steep and the snow too dangerous to venture on. All the guides except one refused to proceed any further, and he led them by a route which he called a “knife-blade,” sometimes on hands and knees, and always with their poles testing the way before them. For another hour, through increasing mist, they por- severed; the barometer showed them an altitude of 18,380 feet; and here they began to suffer from the rarefaction of the air. They breathed with difficulty, their heads swam, and their eyes became suffused with blood. Condors cam( sweeping down the terrible pass. Once the mists parted, and they beheld the vast dome so near to them that tli ey believed they should certainly reach the summit. They hurried on, but all at once their further progress was stopped by a vast chasm four hundred feet deep and sixty feet wide. They had attained a hight of 19,200 feet. They descended the mountain in a storm of hail and snow. In another excursion they crossed a bridge one hundred and twenty feet long, formed of ropes, manufactured from the fibrous roots of the Aguava Americana, three or four inches in diameter. It was by a bridge of this kind that a permanent communication was kept open between Lima and Quito. On their way to Cotopaxi they saw the house of the Inca Huayna- Capac. It formed a square of one hundred feet with walls of burnt porphyry, three feet thick, and the stones as regularly wrought as in Roman buildings. The doors were similar to those of the ancient Egyptian temples. : . IS THE FIFTH Avenue Pavement a Failure 1 We recently stated, in the SCIENTIFIC AMERICAN, that a covering of asphalt and gravel was in process of being laid over the pavement on the Fifth Avenue. The work is now completed, and it is certainly a great relief from noise to the residents of the avenue, and a luxury to those who ri<Je over it; but we fear that the result will prove unsatisfactory, as already there are many visible signs of injury to the surface. It is still our belief, and we so expressed it to the person in charge of the work, that vehicles were allowed to run over the covering before it had become sufficiently seasoned. The result, we fear, is likely to prove that the experiment, so far as Fifth Avenue is coneerned, is a failure. © 1869 SCIENTIFIC AMERICAN, INC.