Mechanical Notation.This also has been described in a former chapter. I look upon it as one of the most important additions I have made to human knowledge. It has placed the construction of machinery in the rank of a demonstrative science. The day will arrive when no school of mechanical drawing will be thought complete without teaching it.Occulting Lights.〈PRINCIPLE OF INVENTION.〉The great object of all my inquiries has ever been to endeavour to ascertain those laws of thought by which man makes discoveries. It was by following out one of the principles which I had arrived at that I was led to the system of occulting numerical lights for distinguishing lighthouses{453}and for night signals at sea, which I published about twelve years ago. The principle I allude to isthis:—Whenever we meet with any defect in the means we are contriving for the accomplishing a given object, that defect should be noted and reserved for future consideration, and inquiry should bemade—Whether that which is a defect as regards the object in view may not become a source of advantage in some totally different subject.I had for a long series of years been watching the progress of electric, magnetic, and other lights of that order, with the view of using them for domestic purposes; but their want of uniformity seemed to render them hopeless for that object. Returning from a brilliant exhibition of voltaic light, I thought of applying the above rule. The accidental interruptions might, by breaking the circuit, be made to recur at any required intervals. This remark suggested their adaptation to a system of signals. But it was immediately followed by another, namely: that the interruptions were equally applicable to all lights, and might be effected by simple mechanism.〈UNEXPECTED DIFFICULTY.〉I then, by means of a small piece of clock-work and an argand lamp, made anumericalsystem of occultation, by which any number might be transmitted to all those within sight of the source of light. Having placed this in a window of my house, I walked down the street to the distance of about 250 yards. On turning round I perceived the number 32 clearly indicated by its occultations. There was, however, a small defect in the apparatus. After each occultation there was a kind of semi-occultation. This arose from the arm which carried the shade rebounding from the stop on which it fell. Aware that this defect could be easily remedied, I{454}continued my onward course for about 250 yards more, with my back towards the light. On turning round I was much surprised to observe that the signal 32 was repeated distinctly without the slightest trace of any semi-occultation or blink.I was very much astonished at this change; and on returning towards my house had the light constantly in view. After advancing a short distance I thought I perceived a very faint trace of the blink. At thirty or forty paces nearer it was clearly visible, and at the half-way point it was again perfectly distinct. I knew that the remedy was easy, but I was puzzled as to the cause.After a little reflection I concluded that it arose from the circumstance that the small hole through which the light passed was just large enough to be visible at five hundred yards, yet that when the same hole was partially covered by the rebound there did not remain sufficient light to be seen at the full distance of five hundred yards.Thus prepared, I again applied the principle I had commenced with and proceeded to examine whether this defect might not be converted into an advantage.〈OCCULTING SIGNALS.〉I soon perceived that a lighthouse, whose number was continually repeated with a blink, obscuring just half its light, would be seenwithout any blinkat all distances beyond half its range; but that at all distances within its half range that fact would be indicated by a blink. Thus with two blinks, properly adjusted, the distance of a vessel from a first-class light would be distinguished at from twenty to thirty miles by occultations indicating its number without any blink; between ten and twenty miles by an occultation with one blink, and within ten miles by an occultation with two blinks.But another advantage was also suggested by this defect.{455}If the opaque cylinder which intercepts the light consists of two cylinders, A and B, connected together by rods:thus—If the compound cylinder descend toa, and then rise again, there will be a single occultation.If the compound cylinder descend tob, and then rise again, there will be a double occultation.If the compound cylinder descend toc, and then rise again, there will be a triple occultation.Such occultations are very distinct, and are specially applicable to lighthouses.In the year 1851, during the Great Exhibition, the light I have described was exhibited from an upper window of my house in Dorset Street during many weeks. It had not passed unnoticed by foreigners, who frequently reminded me that they had passed my door when I was asleep by writing upon their card the number exhibited by the occulting light and dropping it into my letter-box.About five or six weeks after its first appearance I received a letter from a friend of mine in the United States, expressing great interest about it, and inquiring whether its construction was a secret. My answer was, that I made no{456}secret of it, and would prepare and send him a short description of it.I then prepared a description, of which I had a very few copies printed. I sent twelve of these to the proper authorities of the great maritime countries. Most of them were accompanied by a private note of my own to some person of influence with whom I happened to be acquainted.One of these was addressed to the present Emperor of the French, then a member of their Representative Chamber. It was dated the 30th November, 1852. Three days after I read in the newspapers the account of thecoupof December 2, and smiled at the inopportune time at which my letter had accidentally been forwarded. However, three days after I received from M. Mocquard the prettiest note, saying that he was commanded by the Prince President to thank me for the communication, and to assure me that the Prince was as much attached as ever to science, and should always continue to promote its cultivation.〈EXPERIMENTS IN AMERICA.〉The letter which was sent to the United States was placed in the hands of the Coast Survey. The plan was highly approved, and Congress made a grant of 5,000 dollars, in order to try it experimentally. After a long series of experiments, in which its merits were severely tested, a report was made to Congress strongly recommending its adoption. I then received a very pressing invitation to visit the United States, for the purpose of assisting to put it in action. It was conveyed to me by an amiable and highly cultivated person, the late Mr. Reed, Professor of English Literature at Philadelphia, who, on his arrival in London, proposed that I should accompany him on his return in October, the best season for the voyage, and in the finest vessel of their mercantile navy. I had long had a great wish to visit the American continent, but I did{457}not think it worth crossing the Atlantic, unless I could have spent a twelvemonth in America. Finding this impossible under the then circumstances, about a month before the time arrived I resigned with great reluctance the pleasure of accompanying my friend to his own country.〈THE AUTHOR’S ESCAPE.〉It was most fortunate that I was thus prevented from embarking on board the Arctic, a steamer of the largest class.Steaming at the rate of thirteen knots an hour over the banks of Newfoundland during a dense fog, the Arctic was run into by a steamer of about half its size, moving at the rate of seven knots. The concussion was in this instance fatal to the larger vessel.This sad catastrophe was thus described by the brother of my lostfriend:—“On the 20th of September, 1854, Mr. Reed, with his sister, embarked at Liverpool for New York, in the United States steamship Arctic. Seven days afterwards, at noon, on the 27th, when almost in sight of his native land, a fatal collision occurred, and before sundown every human being left upon the ship had sunk under the waves of the ocean. The only survivor who personally acquainted with my brother, saw him about two o’clock,P.M., after the collision, and not very long before the ship sank, sitting with his sister in the small passage aft of the dining-saloon. They were tranquil and silent, though their faces wore the look of painful anxiety. They probably afterwards left this position, and repaired to the promenade deck. For a selfish struggle for life, with a helpless companion dependent upon him, with a physical frame unsuited for such a strife, and above all, with a sentiment of religious resignation which taught him in that hour of agony, even with the memory of his wife and children thronging in his mind, to bow his head in{458}submission to the will of God,—for such a struggle he was wholly unsuited; and his is the praise, that he perished with the women and children.”〈OCCULTING LIGHT AT BRUSSELS.〉In 1853 I spent some weeks at Brussels. During my residence in that city a Congress of naval officers from all the maritime nations assembled to discuss and agree upon certain rules and observations to be arranged for the common benefit of all. One evening I had the great pleasure of receiving the whole party at my house for the purpose of witnessing my occulting lights.The portable occulting light which I had brought with me was placed in the verandah on the first floor, and we then went along the Boulevards to see its effect at different distances and with various numerical signals. On our return several papers relating to the subject were lying upon the table. The Russian representative, M.———,took up one of the original printed descriptions and was much interested in it. On taking leave he asked, with some hesitation, whether I would lend it to him for a few hours. I told him at once that if I possessed another copy I would willingly give it to him; but that not being the case I could only offer to lend it. M.———therefore took it home with him, and when I sat down to breakfast the next morning I found it upon my table. In the course of the day I met my Russian friend in the Park. I expressed my hope that he had been interested by the little tract he had so speedily returned. He replied that it had interested him so much that he had sat up all night, had copied the whole of it, and that his transcript and a despatch upon the subject was now on its way by the post to his own Government.Several years after I was informed thatocculting solar lights{459}were used by the Russians during the siege of Sebastopol.
This also has been described in a former chapter. I look upon it as one of the most important additions I have made to human knowledge. It has placed the construction of machinery in the rank of a demonstrative science. The day will arrive when no school of mechanical drawing will be thought complete without teaching it.
〈PRINCIPLE OF INVENTION.〉
The great object of all my inquiries has ever been to endeavour to ascertain those laws of thought by which man makes discoveries. It was by following out one of the principles which I had arrived at that I was led to the system of occulting numerical lights for distinguishing lighthouses{453}and for night signals at sea, which I published about twelve years ago. The principle I allude to isthis:—
Whenever we meet with any defect in the means we are contriving for the accomplishing a given object, that defect should be noted and reserved for future consideration, and inquiry should bemade—
Whether that which is a defect as regards the object in view may not become a source of advantage in some totally different subject.
I had for a long series of years been watching the progress of electric, magnetic, and other lights of that order, with the view of using them for domestic purposes; but their want of uniformity seemed to render them hopeless for that object. Returning from a brilliant exhibition of voltaic light, I thought of applying the above rule. The accidental interruptions might, by breaking the circuit, be made to recur at any required intervals. This remark suggested their adaptation to a system of signals. But it was immediately followed by another, namely: that the interruptions were equally applicable to all lights, and might be effected by simple mechanism.
〈UNEXPECTED DIFFICULTY.〉
I then, by means of a small piece of clock-work and an argand lamp, made anumericalsystem of occultation, by which any number might be transmitted to all those within sight of the source of light. Having placed this in a window of my house, I walked down the street to the distance of about 250 yards. On turning round I perceived the number 32 clearly indicated by its occultations. There was, however, a small defect in the apparatus. After each occultation there was a kind of semi-occultation. This arose from the arm which carried the shade rebounding from the stop on which it fell. Aware that this defect could be easily remedied, I{454}continued my onward course for about 250 yards more, with my back towards the light. On turning round I was much surprised to observe that the signal 32 was repeated distinctly without the slightest trace of any semi-occultation or blink.
I was very much astonished at this change; and on returning towards my house had the light constantly in view. After advancing a short distance I thought I perceived a very faint trace of the blink. At thirty or forty paces nearer it was clearly visible, and at the half-way point it was again perfectly distinct. I knew that the remedy was easy, but I was puzzled as to the cause.
After a little reflection I concluded that it arose from the circumstance that the small hole through which the light passed was just large enough to be visible at five hundred yards, yet that when the same hole was partially covered by the rebound there did not remain sufficient light to be seen at the full distance of five hundred yards.
Thus prepared, I again applied the principle I had commenced with and proceeded to examine whether this defect might not be converted into an advantage.
〈OCCULTING SIGNALS.〉
I soon perceived that a lighthouse, whose number was continually repeated with a blink, obscuring just half its light, would be seenwithout any blinkat all distances beyond half its range; but that at all distances within its half range that fact would be indicated by a blink. Thus with two blinks, properly adjusted, the distance of a vessel from a first-class light would be distinguished at from twenty to thirty miles by occultations indicating its number without any blink; between ten and twenty miles by an occultation with one blink, and within ten miles by an occultation with two blinks.
But another advantage was also suggested by this defect.{455}If the opaque cylinder which intercepts the light consists of two cylinders, A and B, connected together by rods:thus—
Such occultations are very distinct, and are specially applicable to lighthouses.
In the year 1851, during the Great Exhibition, the light I have described was exhibited from an upper window of my house in Dorset Street during many weeks. It had not passed unnoticed by foreigners, who frequently reminded me that they had passed my door when I was asleep by writing upon their card the number exhibited by the occulting light and dropping it into my letter-box.
About five or six weeks after its first appearance I received a letter from a friend of mine in the United States, expressing great interest about it, and inquiring whether its construction was a secret. My answer was, that I made no{456}secret of it, and would prepare and send him a short description of it.
I then prepared a description, of which I had a very few copies printed. I sent twelve of these to the proper authorities of the great maritime countries. Most of them were accompanied by a private note of my own to some person of influence with whom I happened to be acquainted.
One of these was addressed to the present Emperor of the French, then a member of their Representative Chamber. It was dated the 30th November, 1852. Three days after I read in the newspapers the account of thecoupof December 2, and smiled at the inopportune time at which my letter had accidentally been forwarded. However, three days after I received from M. Mocquard the prettiest note, saying that he was commanded by the Prince President to thank me for the communication, and to assure me that the Prince was as much attached as ever to science, and should always continue to promote its cultivation.
〈EXPERIMENTS IN AMERICA.〉
The letter which was sent to the United States was placed in the hands of the Coast Survey. The plan was highly approved, and Congress made a grant of 5,000 dollars, in order to try it experimentally. After a long series of experiments, in which its merits were severely tested, a report was made to Congress strongly recommending its adoption. I then received a very pressing invitation to visit the United States, for the purpose of assisting to put it in action. It was conveyed to me by an amiable and highly cultivated person, the late Mr. Reed, Professor of English Literature at Philadelphia, who, on his arrival in London, proposed that I should accompany him on his return in October, the best season for the voyage, and in the finest vessel of their mercantile navy. I had long had a great wish to visit the American continent, but I did{457}not think it worth crossing the Atlantic, unless I could have spent a twelvemonth in America. Finding this impossible under the then circumstances, about a month before the time arrived I resigned with great reluctance the pleasure of accompanying my friend to his own country.
〈THE AUTHOR’S ESCAPE.〉
It was most fortunate that I was thus prevented from embarking on board the Arctic, a steamer of the largest class.
Steaming at the rate of thirteen knots an hour over the banks of Newfoundland during a dense fog, the Arctic was run into by a steamer of about half its size, moving at the rate of seven knots. The concussion was in this instance fatal to the larger vessel.
This sad catastrophe was thus described by the brother of my lostfriend:—
“On the 20th of September, 1854, Mr. Reed, with his sister, embarked at Liverpool for New York, in the United States steamship Arctic. Seven days afterwards, at noon, on the 27th, when almost in sight of his native land, a fatal collision occurred, and before sundown every human being left upon the ship had sunk under the waves of the ocean. The only survivor who personally acquainted with my brother, saw him about two o’clock,P.M., after the collision, and not very long before the ship sank, sitting with his sister in the small passage aft of the dining-saloon. They were tranquil and silent, though their faces wore the look of painful anxiety. They probably afterwards left this position, and repaired to the promenade deck. For a selfish struggle for life, with a helpless companion dependent upon him, with a physical frame unsuited for such a strife, and above all, with a sentiment of religious resignation which taught him in that hour of agony, even with the memory of his wife and children thronging in his mind, to bow his head in{458}submission to the will of God,—for such a struggle he was wholly unsuited; and his is the praise, that he perished with the women and children.”
“On the 20th of September, 1854, Mr. Reed, with his sister, embarked at Liverpool for New York, in the United States steamship Arctic. Seven days afterwards, at noon, on the 27th, when almost in sight of his native land, a fatal collision occurred, and before sundown every human being left upon the ship had sunk under the waves of the ocean. The only survivor who personally acquainted with my brother, saw him about two o’clock,P.M., after the collision, and not very long before the ship sank, sitting with his sister in the small passage aft of the dining-saloon. They were tranquil and silent, though their faces wore the look of painful anxiety. They probably afterwards left this position, and repaired to the promenade deck. For a selfish struggle for life, with a helpless companion dependent upon him, with a physical frame unsuited for such a strife, and above all, with a sentiment of religious resignation which taught him in that hour of agony, even with the memory of his wife and children thronging in his mind, to bow his head in{458}submission to the will of God,—for such a struggle he was wholly unsuited; and his is the praise, that he perished with the women and children.”
〈OCCULTING LIGHT AT BRUSSELS.〉
In 1853 I spent some weeks at Brussels. During my residence in that city a Congress of naval officers from all the maritime nations assembled to discuss and agree upon certain rules and observations to be arranged for the common benefit of all. One evening I had the great pleasure of receiving the whole party at my house for the purpose of witnessing my occulting lights.
The portable occulting light which I had brought with me was placed in the verandah on the first floor, and we then went along the Boulevards to see its effect at different distances and with various numerical signals. On our return several papers relating to the subject were lying upon the table. The Russian representative, M.———,took up one of the original printed descriptions and was much interested in it. On taking leave he asked, with some hesitation, whether I would lend it to him for a few hours. I told him at once that if I possessed another copy I would willingly give it to him; but that not being the case I could only offer to lend it. M.———therefore took it home with him, and when I sat down to breakfast the next morning I found it upon my table. In the course of the day I met my Russian friend in the Park. I expressed my hope that he had been interested by the little tract he had so speedily returned. He replied that it had interested him so much that he had sat up all night, had copied the whole of it, and that his transcript and a despatch upon the subject was now on its way by the post to his own Government.
Several years after I was informed thatocculting solar lights{459}were used by the Russians during the siege of Sebastopol.