Passages from the Life of a Philosopher

Difference Engine No. 2 — The Earl of Rosse, President of the Royal Society, proposed to the Government a Plan by which the Difference Engine No. 2 might have been executed — It was addressed to the Earl of Derby, and rejected by his Chancellor of the Exchequer. IT was not until 1848, when I had mastered the subject of the Analytical Engine, that I resolved on making a complete set of drawings of the Difference Engine No. 2. In this I proposed to take advantage of all the improvements and simp­li­fi­ca­tions which years of unwearied study had produced for the Analytical Engine. In 1852, the Earl of Rosse, who, from its commencement, had looked forward with the greatest interest to the application of mechanism to purposes of calculation, and who was well acquainted with the drawings and notations of the Difference Engine No. 2, inquired of me whether I was willing to give them to the Government, provided they would have the Engine constructed. My feeling was, after the sad experience of the past, that I ought not to think of sacrificing any further portion of my life upon the subject. If, however, they chose to have the Difference Engine made, I was ready to give them the whole of the drawings, and also the notations by which it was dem­on­strated that such a machine could be constructed, and that when made it would necessarily do the work prescribed for it. {98} My much-valued friend, the late Sir Benjamin Hawes, had also been consulted, and it was agreed that the draft of a letter to Lord Derby, who was then prime minister, should be prepared; in which I should make this offer. Lord Rosse proposed to place my letter in Lord Derby’s hands, with his own statement of a plan by which the whole question might be determined. Lord Rosse’s suggestion was, that the Government should apply to the President of the Institution of Civil Engineers to ascertain, 1st. Whether it was possible, from the drawings and notations, to make an estimate of the cost of constructing the machine? 2ndly. In case this question was answered in the affirmative—then, could a Mechanical Engineer be found who would undertake to construct it, and at what expense? The Institution of Civil Engineers was undoubtedly the highest authority upon the first question. That being decided in the affirmative, no other body had equal power to find out those mechanical engineers who might be willing to undertake the contract. Supposing both these questions, or even the latter only, answered in the negative, the proposition, of course, fell to the ground. But if they were both answered in the affirmative, then there would have arisen a further question for the consideration of the Government: namely, Whether the object to be obtained was worthy of the expenditure? 〈LORD ROSSE’S ADDRESS TO THE ROYAL SOCIETY.〉 The final result of this eminently practical plan was communicated to the Royal Society by their President, in his address at their anniversary on the 30th November, 1854. The following is an extract:— {99} “The progress of the work was suspended: there was a change of Government. Science was weighed against gold by a new standard, and it was resolved to proceed no further. No enterprise could have had its beginning under more auspicious circumstances: the Government had taken the initiative—they had called for advice, and the adviser was the highest scientific authority in this country;—your Council; guided by such men as Davy, Wollaston, and Herschel. By your Council the undertaking was inaugurated,—by your Council it was watched over in its progress. That the first great effort to employ the powers of calculating mechanism, in aid of the human intellect, should have been suffered in this great country to expire fruitless, because there was no tangible evidence of immediate profit, as a British subject I deeply regret, and as a Fellow my regret is accompanied with feelings of bitter disappointment. Where a question has once been disposed of, succeeding Governments rarely reopen it, still I thought I should not be doing my duty if I did not take some opportunity of bringing the facts once more before Government. Circumstances had changed, mechanical engineering had made much progress; the tools required and trained workmen were to be found in the workshops of the leading mechanists, the founder’s art was so advanced that casting had been substituted for cutting, in making the change wheels, even of screw-cutting engines, and therefore it was very probable that persons would be found willing to undertake to complete the Difference Engine for a specific sum. “That finished, the question would then have arisen, how far it was advisable to endeavour, by the same means, to turn to account the great labour which had been expended under the guidance of inventive powers the most original, {100} controlled by mathematics of a very high order; and which had been wholly devoted for so many years to the great task of carrying the powers of calculating machinery to its utmost limits. Before I took any step I wrote to several very eminent men of science, inquiring whether, in their opinion, any great scientific object would be gained if Mr. Babbage’s views, as explained in Ménabrèa’s little essay, were completely realized. The answers I received were strongly in the affirmative. As it was necessary the subject should be laid before Government in a form as practical as possible, I wrote to one of our most eminent mechanical engineers to inquire whether I should be safe in stating to Government that the expense of the Calculating Engine had been more than repaid in the improvements in mechanism directly referable to it; he replied,—unquestionably. Fortified by these opinions, I submitted this proposition to Government:—that they should call upon the President of the Society of Civil Engineers to report whether it would be practicable to make a contract for the completion of Mr. Babbage’s Difference Engine, and if so, for what sum. This was in 1852, during the short administration of Lord Derby, and it led to no result. The time was unfortunate; a great political contest was impending, and before there was a lull in politics, so that the voice of Science could be heard, Lord Derby’s government was at an end.” 〈MR. BABBAGE’S LETTER TO THE EARL OF DERBY.〉 The following letter was then drawn up, and placed in Lord Derby’s hands by Lord Rosse:— June 8, 1852. MY LORD, I TAKE the liberty of drawing your Lordship’s attention to the subject of the construction of a Difference Engine, for {101} calculating and printing Astronomical and Nautical Tables, which was brought under the notice of the Government so far back as the year 1823, and upon which the Government of that day desired the opinion of the Royal Society. I annex a copy of the correspondence which took place at that time, and which your Lordship will observe was laid before Parliament. The Committee of the Royal Society, to which the subject was referred, reported generally that the invention was one “fully adequate to the attainment of the objects proposed by the inventor, and that they considered Mr. Babbage as highly deserving of public encouragement in the prosecution of his arduous undertaking.”—Report of Royal Society, 1 st May, 1823. Parliamentary Paper, 370, 22 nd May, 1823. And in a subsequent and more detailed Report, which I annex also, they state:— “The Committee have no intention of entering into any consideration of the abstract math­e­mat­i­cal principle on which the practicability of such a machine as Mr. Babbage’s relies, nor of its public utility when completed. They consider the former as not only sufficiently clear in itself, but as already admitted and acted on by the Council in their former proceedings. The latter they regard as obvious to every one who considers the immense advantage of accurate numerical Tables in all matters of calculation, especially in those which relate to Astronomy and Navigation, and the great variety and extent of those which it is the object and within the compass of Mr. Babbage’s Engine to calculate and print with perfect accuracy.”—Report of Committee of Royal Society, 12th Feb., 1829. Upon the first of these Reports, the Government determined to construct the machine, under my personal {102} superintendence and direction. The Engine was accordingly commenced and partially completed. Tables of figures were calculated, limited in extent only by the number of wheels put together. Delays, from various causes arose in the progress of the work, and great expenses were incurred. The machine was altogether new in design and construction, and required the utmost mechanical skill which could be obtained for its execution. “It involved,” to quote again from the Report of the Committee of the Royal Society, “the necessity of constructing, and in many instances inventing, tools and machinery of great expense and complexity (and in many instances of ingenious contrivances likely to prove useful for other purposes hereafter), for forming with the requisite precision parts of the apparatus dissimilar to any used in ordinary mechanical works; that of making many previous trials to ascertain the validity of proposed movements; and that of altering, improving, and simplifying those already contrived and reduced to drawings. Your Committee are so far from being surprised at the time it has occupied to bring it to its present state, that they feel more disposed to wonder it has been possible to accomplish so much.” The true explanation both of the slow progress and of the cost of the work is clearly stated in this passage; and I may remark in passing, that the tools which were invented for the construction of the machine were afterwards found of utility, and that this anticipation of the Committee has been realized, as some of our most eminent mechanical engineers will readily testify. Similar circumstances will, I apprehend, always attend and prolong the period of bringing to perfection inventions which have no parallel in the previous history of mechanical {103} construction. The necessary science and skill specially acquired in executing such works must also, as experience is gained, suggest deviations from, and improvements in, the original plan of those works; and the adoption or rejection of such changes, especially under circumstances similar to those in which I was placed, often involves questions of the greatest difficulty and anxiety. From whatever cause, however, the delays and expenses arose, the result was that the Government was discouraged, and declined to proceed further with the work. Mr. Goulburn’s letter, intimating this decision to me, in 1842, will be found in the accompanying printed Statement. And that the impediments to the completion of the engine, described by the Royal Society, were those which influenced the Government in the determination they came to, I infer from the reason assigned by Mr. Goulburn for its discontinuance, viz., “the expense which would be necessary in order to render it either sat­is­fac­tory to yourself or generally useful.” I readily admit that the work could not have been rendered sat­is­fac­tory to myself unless I was free to introduce every improvement which experience and thought could suggest. But that even with this additional source of expense its general usefulness would have been impaired, I cannot assent to, for I believe, in the words of the Report I have already quoted, the “immense advantage of accurate Numerical Tables in all matters of calculation, especially in those which relate to Astronomy and Navigation, cannot, within any reasonable limits, be over-estimated.” As to the expense actually incurred upon the first Difference Engine, that of the Government was about 17,000 l. On my own part, and out of my own private resources, I have sacrificed upon this and other works of science upwards of 20,000 l. {104} From the date of Mr. Goulburn’s letter, nothing has been done towards the further completion of the Difference Engine by the Government or myself. So much of it as was completed was deposited in the Museum of King’s College, where it now remains. Three consequences have, however, resulted from