The following extract from an unpublished manuscript by Robison himself will show at once the estimation in which Watt was held, and will illustrate one of the most interesting traits of his personal character:—
"I had always, from my earliest youth, a great relish for the natural sciences, and particularly for mathematical and mechanical philosophy, when I was introduced by Drs. Simson, Dick, and Moor, gentlemen eminent for their mathematical abilities, to Mr. Watt. I saw a workman, and expected no more; but was surprised to find a philosopher as young as myself, and always ready to instruct me. I had the vanity to think myself a pretty good proficient in my favourite study, and was rather mortified at finding Mr. Watt so much my superior.. .. Whenever any puzzle came in the way of any of the young students, we went to Mr. Watt. He needed only to be prompted, for every thing became to him the beginning of a new and serious study, and we knew that he would not quit it till he had either discovered its insignificancy, or had made something of it. He learnt the German language in order to peruse Leupold's 'Theatrum Machinarum;' so did I, to know what he was about. Similar reasons made us both learn the Italian language. * * * When to his superiority of knowledge is added the naïve simplicity and candour of Mr. Watt's character, it is no wonder that the attachment of his acquaintances was strong. I have seen something of the world, and am obliged to say I never saw such another instance of general and cordial attachment to a person whom all acknowledged to be their superior. But that superiority was concealed under the most amiable candour, and a liberal allowance of merit to every man. Mr. Watt was the first to ascribe to the ingenuity of a friend things which were nothing but his own surmises, followed out and embodied by another. I am the more entitled to say this, as I have often experienced it in my own case."
Watt never permitted the inquiries which arose out of these reunions to interfere with the discharge of the duties of his workshop. There he passed the day, devoting the [Pg083] night to study. Every inquiry appeared to him to be attractive in proportion to its difficulty, and to have charms in proportion as it was removed from the common routine of his business. As an example of this may be mentioned the fact, that, being himself so insensible to the charms of music that he could not distinguish one note from another, he was actually induced to undertake the construction of an organ, in which he was nevertheless completely successful. The instrument he constructed, as might have been expected, contained many improvements in its mechanism; but what is much more remarkable, its tone and its musical qualities commanded the admiration of all the professional musicians who heard it. In the construction of this instrument Watt showed that vigorous spirit of investigation which characterised all the subsequent labours of his life. He made out the scale of temperament by the aid of the phenomena of beats, of which he could only obtain a knowledge by a profound but obscure work published by Dr. Robert Smith of Cambridge.
The earliest occasion on which the attention of Watt is said to have been called to the agency of steam, was in the year 1759, when his friend Robison entertained some speculations for applying that agent as a means of propelling wheel carriages; and he consulted Watt on the subject. No record, however, has been preserved of any experiments which were tried on this occasion; nor does it appear that the inquiry was carried farther than a verbal discussion, such as habitually took place on other subjects of science between Watt and his friends.
(46.)
It is usual to provide, in the cabinets of experimental apparatus for the instruction of the students of universities, [Pg084] small working models of the most useful machines. In the collection for the illustration of the lectures delivered to the Natural Philosophy class in the University of Glasgow was a working model of Newcomen's atmospheric engine, applied to a pump for raising water; which, however, had never been found to work satisfactorily. The Professor of Experimental Philosophy of that day, Dr. John Anderson (the founder of the celebrated Andersonian Institution), sent this model in 1763 to Watt's workshop, to be repaired. Its defects soon disappeared, and it was made to work to the satisfaction of the professor and students.
This simple discharge of his duty, however, did not satisfy the artisan; and his wonted activity of mind rendered this model a subject of profound meditation, and led him into a course of practical inquiry respecting it, which formed the commencement of a most brilliant career of mechanical discovery. The improvement—we might almost say the creation—of the steam engine, by this great man, must not therefore be regarded, as so often happens with mechanical discoveries, as the result of fortuitous observation, or even of a felicitous momentary inspiration. Watt, on the other hand, conducted his investigation by a course of deep thought, and of experiments marked by the last refinement of delicacy and address. If he had received a more extended and liberal education, one would have thought that he had adopted for his guide the celebrated maxim of Bacon:—
"To write, speak, meditate, or act, when we are not provided with facts to direct our thoughts, is to navigate a coast full of dangers without a pilot, and to launch into the immensity of the ocean without either rudder or compass."
The model which he had repaired, had a cylinder of only two inches diameter, and six inches stroke. After he had put it in complete order, he found, that although the boiler was much larger in proportion to the cylinder than those of real engines, yet, that it was incapable of supplying the cylinder with steam in sufficient quantity to keep it at work. To enable it to continue to move, he found it necessary to lessen the quantity of water raised by its pump, so as to [Pg085] reduce the load on its piston very much below the proper standard according to the common rules for large engines.
He ascribed the great inferiority in the performance of the model, compared with the performance of the large engines, to the small size of the cylinder, and to its material. The cylinder of the model was brass, while those of large engines were of cast iron; and brass being a better conductor of heat than iron, he concluded that more heat in proportion was lost from this cause in the model, than in the larger engines. He observed that the small cylinder was so heated when the steam was admitted into it, that it could not be touched by the hand; but, nevertheless, that this heat contributed nothing to its performance, inasmuch as before the piston descended, the cylinder required to be cooled.