Patrick Forbes to Faraday   7 October 1839¹

King's College, Aberdeen, Oct. 7, 1839.

My dear Sir,

Having just seen a notice from Mr. Jacobi sent by you to the London and Edinburgh Philosophical Magazine², regarding the success of his experiments on the production of a moving power by electro-magnetism, I am sure it will give you pleasure to know that a countryman of our own, Mr. Robert Davidson³, of this place, has been eminently successful in his labours in the same field of discovery. For in the first place, he has an arrangement by which with only two electro-magnets and less than one square foot of zinc-surface (the negative metal being copper) a lathe is driven with such velocity as to be capable of turning small articles. Secondly, he has another arrangement, by which, with the same small extent of galvanic power, a small carriage is driven on which two persons were carried along a very coarse wooden floor of a room. And he has a third arrangement, not yet completed, by which, from the imperfect experiments he has made, he expects to gain very considerably more force from the same extent of galvanic power than from either of the other two.

The first of these arrangements were seen in operation by Dr. Fleming⁴, Professor of Natural Philosophy in this University, and myself, some days ago; and there remains no doubt on our minds that Mr. Davidson's arrangements will, when finished, be found available as a highly useful, efficient, and exceedingly simple moving power. He has been busily employed for the last two years in his attempts to perfect his machines, during all which time I have been acquainted with his progress, and care bear testimony to the great ingenuity he has shown in overcoming the numberless difficulties he has had to encounter. So far as I know, he was the first who employed the electro-magnetic power in producing motion by simply suspending the magnetism without a change of the poles. This he accomplished about two years ago. About the same time he also constructed galvanic batteries on Professor Daniell's plan⁵ by substituting a particular sort of canvas instead of gut, which substitution answers perfectly, is very durable, and can be made of any form or size. And lastly, he has ascertained the kind of iron, and the mode of working it into the best state for producing the strongest magnets with certainty.

The first two machines, seen in operation by Dr. Fleming and myself, are exceedingly simple, without indeed the least complexity, and therefore easily manageable, and not liable to derangement. They also take up very little room. As yet the extent of the power of which they are capable has not been at all ascertained, as the size of the battery employed is so trifling and the magnets so few: but from what can be judged by what is already done, it seems to be probable that a very great power, in no degree even inferior to that of steam, but much more manageable, much less expensive, and occupying greatly less space, if the coals be taken into account, may be obtained.

In short, the inventions of Mr. Davidson seem to be so interesting to rail-road proprietors in particular that it would be much for their interest to take up the subject, and be at the expense of making the experiments necessary to bring this power into operation on the great scale, which indeed would be very trifling to a company, while it is very serious for an individual by no means rich, and who has already expended so much of his time and money from the mere desire of perfecting machines which he expected would be so beneficial to his country and to mankind. For it deserves to be mentioned that he has made no secret of his operations, but has shown and explained all that he has done to every one who wished it. His motives have been quite disinterested, and I shall deem it a reproach to our country and countrymen if he is allowed to languish in obscurity, and not have an opportunity afforded him of perfecting his inventions and bringing them into operation, when then promise to be productive of such incalculable advantages.

I am, my dear Sir, yours, &c. | Pat. Forbes.

Michael Faraday, D.C.L., &c. &c.