1871 Scientific American  
Although somewhat late to communicate with you upon this subject, I wish to express my surprise that such a con clusion should have been arrived at by the coroner and his jury, as to have caused the President of the line and engineer of the boat to have been arrested as the parties responsible for the disaster. The Government, in view of the ignorance, of steamboat engineers and the public generally, of the strength of boiler materials to withstand stationary and vibrating pressures, attempted
more » ... o regulate matters by prescribing that hydrostatic tests and examinations be made by certain inspectors of more (Jr less ability, and that the persons given charge of steam boat boilers be examindd and licensed. In order to make as· surance doubly sure, a system of compound levers, called a lock up safety valve, has of late years been required to be bolted to each boiler, as a sort of cast iron substitute for brains. Now here is a boiler that is supposed to have passed the required test, and has cast iron brains furnished to it to pre vent the pressure from exceeding the lawful amount, and the engineer duly licensed, and in spite of all this, it blows up and kills a good many people. Now, who is responsible? is what many wise men have been consulted for the purpose of ascertaining. Clearly, th!l Government, and no one else. The inspector takes all responsibility from the owners, and he, acting in accordance with the printed laws and instruc tions, shifts the responsibility to the makers of those instruc tions and laws, whose name is the same as that of the devils in the herd of swine, Legion-rather too many to shut up in the Tomhs. The whole system then is at fault; instead of requiring that all parts of boilers �hould be built to sustain six times their working pressure, or three times their te ,ted pressure, they are usually tested up as high as they will bear for an instant, and the pressure instantly relieved; the working pressure is then certified to be two thirds the highest point reached by the index of the pressure gage. No wonder that boiler makers say that cold water te8ts are bad for boilers. The evils of the present system were brought very clearly to my mind recently, when I had business in the West, re quiring me to tempt Providence by traveling on a Mississippi river steamboat, The boat had four cylindric boilers forty inches diameter and twenty-six feet long, each having two flues fourteen inches diameter. The boilers had been tested at 188 pounds, and the limit of steam pressure was 125t pounds. They were of one quarter inch iron, single riveted. Getting sight of the steam gage, I found it �howing 160 pounds, but I was much pleased when the engineer informed me that it was twenty pounds out of the way, and the real pressure was only 140. One of those shapeless traps called a lock up safety valve was attached, which was so effectually locked up that no steam could issue from it. The other valve was raised by hand when required, which was rarely, as the blow through valve was mostly relied upon when the boat was stopped. I found upon inquiry that the inspector's rule for testing boilers paid no regard to the strength of the flue (although Fairbairn's experiments were published many years since), but were based entirely upon the diameter and thickness of the shell, with a strength (assumed) of 60,000 pounds per square inch in tension. At my first opportunity, Imade the following figures: 60,000+2+2+40=375=burst ing pressure of fore and aft seam; and for the flue, applied . ' p X 93 000 the formula in Haswell's book ' 187 pounds pres-26X14 aure required to collapse the flue. Here then were these flues, that had been tested up to and beyond their cal culated strength, and perhaps flattened in the operation, so they were ready to go at almost any time when the engineer should neglect to open his blow through valves. Should this article cause people to speculate more upon practical pro· babilities regarding boiler explosions, and learn that all boil ers have a limit of strength that should not be e:i:ceeded, we may hope to see steam vessels made safe. to Correspon dents," I promised H. L. C. (who wanted to know how to construct an electrical engine) and T. G. B. (who wished di rections for constructing instruments for learning telegraphy) that I would send them specifications and drawings gratis. This I was prepared to do, but in addition to their letters I have received a score or more from other persons from nearly every State in the Union, and from Canada. I cannot write and send drawings to each separately, and as there seems to be so much interest manifested, I know of no better plan than to ask you to publish, for the benefit of all, a few remarks which I hope will be satisfactory. As only H. L. C. has written about the electrical engine, and as I have answered him explicitly and fully, I will con· fine myself to the means of learning telegraphy without a battery or electromagnet. It will save much time and space to simply state that the instrument which I propose is a slight modification of the Morse" register." I presume every one can obtain a sight of one of them. The modification is simply the removal of the electromagnet, and the addition of a "button" to the outer end of the pen lever, whereby it (the pen lever) is con· � dtntifit �mttitnu. verted into a" key," and all manipulations thereof will be shown on the ribbon of paper as it passes between the roll ers. In some registers 10th the down and back strokes are regulated by double nuts on the post at the outer extremity of the pen lever, but as this arrangement would interfere with the working of the key, two posts (adjustable) should be used; one at the outer end, to receive the down stroke and regulate the depth of the impression in the papl'r, and the other near the inner end to receive the back stroke and regulate the amount of motion. Your readers will understand that this arrangement does not contemplate the transmi;sion of signals to any distance, but simply a register of the manipulations of the learner, who will be able to correct errors which he would not recog nize were he learning by sound. Two persons sitting at such an instrument can transmit messages to each other without having the disagreeable task of keeping a battery in working order; and after considerable practice the letters will be as readily distinguished by sound as by sight. I maintain that by the use of paper in learning, the learner acquires more exactness in the length of dots, dashdB, and spaces than he otherwise would, and that if all the operators now employed had thus learned, very few if any of the egregious blunders constantly occurring would be made. The tailor's dying advice was" Always tie a knot in the end of your thread," and my advice to learners of telegraphy is, always space your letters and words as accurately as a good printer does Practice your letters j and k until the former is different from nn and the latter different from nt or tao Give the dashes their full length, and shorten the dots as much as you choose, but above aU space between your letters and words. In regard to the learner being able to make his own instru· ment, if he is ingenious, skillful, and has the tools and mate rial at hand, he can do so; but I would think it best to apply to some manufacturing electrician who, by the above descrip tion, could make exactly the right thing and furnish a roll of paper with it for about $20. To those who prefer making their own, I would point out some difficulties and necessities, to wit; the pen lever must be hung so that the pen will accurately fit into the groove of the roller, and have not the slightest lateral motion. The rollers must be held together by springs or weights just suf· ficiently to firmly hold and draw the paper. Such an ar· rangement will allow the passage of irregularities, or a " splice" in the paper. The posts must be adjustable, by a perpendicular screw and check nut in their tops. If these conditions be complied wi h, the train of gearing working smoothly, no one will have any difficulty after a little experience in the working of the machine.
doi:10.1038/scientificamerican09091871-164 fatcat:6hw3zuml2zbjhbhfybeqidutjm