The Application of Steam to Canals.—No. 5

George Edward Harding
1871 Scientific American  
�citntifi' �mtti'nn. sition. In extreme contrast to this was a valve which had been in work for twelve years. It had a specific gravity of 75� Ibs. to thA cubic foot, and was probably seven eighths or one inch thick when new, the portions still sound retaining their original elasticity. This val ve, however, was construct ed of n, m:xed rubber, and Mr. Syme considers that rubber to which a metallio pigment is added, in addition to the usual quantity of sulphur for lhorough vulcanization, is
more » ... adapt ed for the construction of air pump valves, the specific grav ity being from 72 Ibs to 77 Ibs. per -:ubic foot. He thinks that pure vulcanized rubber is dissolved and worn away more rapidly when acting in oily water than the" mixed," which is protected by a pigment impermeable by oil or fluid grease. The general conclusions drawn from the examination of these !Specimens were that circuhtr valves should be allowed to ]'0 tate, aml that the angles of the aperturt s in the grid plate and the edges of bearing bars should be rounded off, as when these are left too sharp and the valve beats always in one position, the rubber is cut, and the oil getting in produces a viscid effect in each incision. mere pass examinations, or may be made competit.ive, and that the President of the United States,. as the executive head of the government, might if he chose, without. further hesitation, issue a general order controlling all the depart ments, and establishing therein the principle of competitive examinations. There were circumstances which ren'lered the application of this statute to the Patent Office a matter of comparative ease. If I had been an applicant for the office of Commissioner, and had oLtained it by reason of the active exertions and warm recommendation of Senators and congressmen, I should upon taking office have many debts to pay. It would have been hardly the fair thing to say to one of my Congressional friends that his candidate could not be received on his recommendation, but that he must first pass the ordeal of a stringent examination. He would have replied," Why you were yourself appointed upon m" disregarded, or totally ignored, and was found to be conve nient only for the purpose of getting rid of some man who was sacrifiCed by an unfair application of it, or it was manip ulated for the benefit of some favorite who was allowed to slip through its meshes. It was in bad repute. Instances were current, and were authentic, in which the examiners had been requested to make the proposed test a mere for mality. Many who had been subjected to it were able to tell of trifling q ues tions concerning routes of travel or the s.ate of the weather, or the health of their families, or the welfare of their aged parents, which comprised the total ex amination as to theH education or capacity. _1_'.
doi:10.1038/scientificamerican07151871-32a fatcat:p7wozawrqveltljzrptjwb76vi