I have lately perused the 47th Vol. of the Transactions, wherein I find your very candid and favourable Account of my Electrical papers, for which be pleased to accept my grateful Acknowledgments.

My Friend Mr. Collinson once gave me reason to hope for the pleasure and advantage of a Correspondence with you, by telling me you intended me a Letter. I never received it; and wou’d have wrote to you, but that I heard you was much engaged in business, and I fear’d to incommode you; but the good Opinion of me you are pleased to express in that account, encourages me to think a few lines whose chief aim is the Improvement of knowledge, will not be disagreeable.

I was exceedingly pleased with your curious Account of the Phaenomena of Electricity in Vacuo, which I had long expected but never before seen.

There is but one particular of that account in which I am not yet perfectly Satisfy’d. It is in Page 367. where you seem to think (from observing the Electricity to pass in Vacuo in one continued Stream of the same Dimension, etc.) “that the cause of that very powerfull Repulsion of the Particles of Electrical Fire one to the Other, which we see in Open Air, is more owing to the Resistance of the Air, than to any natural Tendency of the Electricity it self.” etc.

At first View this appears likely; But may not the cause of the Stream’s not Diverging in Vacuo possibly be this, that the inner sides of the Receiver, being first Electrify’d, and having themselves an electric Atmosphere, the same repels every way and operates equally on every side of the Stream so as to confine it, and prevent it’s Expansion? this being the Case even when the Receiver is not exhausted: For let a [two pages missing].

4. That the holes made [in] this Pasteboard by the Electric Strokes afford very equivocal Signs of the Direction, (as I have shown more largely in a Paper to Mr. Collinson) the appearance varying according to the Circumstances.

In the same 47th. Vol: of the Transactions, there is I think a small mistake, page 552. in relation of the Experiment with a pair of Scales; where it is said, that an Electrified Seal was attracted by a Needle, and repelled by an Obtuse Body, which I take to be a reverse of the Fact, and to have led the Gentleman who wrote the Letter, into an Error in the Consequence he Draws from the supposed State of the Experiment.

The Paper abovementioned to Mr. Collinson, contains a Doctrine so seemingly Paradoxical, Viz. That Clouds are most commonly Electrified Negatively, and the Strokes of Lightning therefore most frequently upwards from the Earth of the Cloud That I fear it will be thought whimsical, and that many of your Electricians will scarce think it worth while to repeat the Experiments. I hope however that you will not suffer it to be condemned too hastily; but procure it a fair and thorough Examination.

I am with the greatest Esteem and Respect Sir your most humble servant