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By the Secretary of the interior. In considering a foreign invention in its relation to an American invention, to determine the " flrst inventor," not the actual date of the former, but the date when it was patented or described in a printed publication, is the point to be kept in view. In this connectionjhe invention is patented in England, not at the date of the provisional speciflcation, but when the completed speciflcation is flled. Testimony which would show a date of actual invention in a foreign country earlier than the date when the completed speciflcation was flled would be immaterial in an interference. By the Commissioner of Patents. Where the only purpose of the reissue application is to broaden the Claims, it must clearly appear that there was a mistake or error in the original preparation of the case, and that the applicant took immediate steps to have the same corrected. By a failure to take immediate steps toward correcting a patent the patentee acquiesoeg in the terms of the grant and dedicates the invention to the public use. It has been in-timated by the Supreme Court that they regard two years as the natural limit of delay in such cases in analogy to the provisions of law respecting the public use of an invention. Chimney Flnes and Flre Place. The frequent destruction of buildings by flres caused by imperfect hot air flues, poorly constructed chimneys, and defective flre places impels attention to the lack of safe methods of building brick work in these portions of dwellings and other buildings. It has been found, by investigation after a fire has occurred, that carelessness, haste, 9' parsimoniousness on the part of the architect, the builder, or the owner, had been really responsible for the damage. There are plenty of recorded instances where flres have Started because of the presence of a combustlble in the chimney flue, as a flooring joist passing through the wall of the chimney and forming a part of the inner face of the flue. In one instance the builder's excuse was that the beam was on the upper floor and at least ten feet from a flre on the floor below, and was therefore out of danger. But a Stove was placed so that its doli very flue came within eighteen inches of the exposed beam, and a fire was the ulti-mate result after an entire winter's charring of the beam. There are instances of a division wall for a chimney flue being laid of only half a brick thickness--the brick width-- and the mortar so carelessly applied as to leave chinks between the brick courses. The ledges and projecting ob structions left in unpargeted chimney flues afford inviting | places for the deposit of soot and other light substances carried up with the smoke in its upward flight. Occa- sionally these accumulations take flre, and when a downward blowing gust occurs, the flne particles, all agiow, may be driven through the unprotected interstices of the unren-dered brick wall to Start a flre between floor and ceiling, or in the vertical space between plaster and studding. The Building News (English) takes up this matter of imperfect chimney building, and suggests, among other pre-cautions, the lining of chimney flues with tubes of flre brick and the Alling of the angles between the circular tubing and the Square section of the chimney with solid brick work. To some extent this System is inuse in this country, vitrifled drain tile being employed for the purpose. The News advocates the thorough pargeting, or plaster coating, of the interior of all chimney flues, where this flre-proof tubing js not used, so as to stopup all possible crevices that may have been left by the carelessness of the masons. Chimney walls ought, also, to be carried up nine inches thick to a height of six feet above any flre, as the passage of heat through a biick wall is very perceptible, even if there is not a strong draught. Angles in the course of chimney flues should be of unusual thickness of brick, and be thoroughly plastered, as they present a face to the im-pact of the heated gases in their upward tendency. Whatever other precautions are required, it is certain that wood or other combustlble substances should not be brought in contignity with the chimney or the flre place. The present revival of the old fashioned fire place makes these cautions peculiarly signiflcant. Quite recently the owner of a new house, which had a "low down "flre place for wood burning, discovered that the stone slab forming the flre bottom and hearth was supported on cross beams of spruceasa foundation, leaving only three inches, or less, of a heat conducling material between the flre and the wood. These conditions, so favorable to a destructive flre, were remedied at once.
