From David Colden7
Draft: New-York Historical Society
August 12th. 1756
You oblidged me very much by communicating your Electrical Experiments made in pursuance of those by Mr. Canton:8 I shall think myself fully rewarded for my attempts in Electricity if I can thereby procure the notice of one whose Labours always aford agreable instruction to those who are desirous of discovering truth.
Altho’ I have not intirely laid aside Electrical Amusements yet I have not discoverd many effects worth communicating to you, One only has appeard which I do not remember to have seen taken notice of, viz. That when a Glass Tube is Excited the inner Surface of it has the Electric fire as much accumulated on it, as the outer or that which is rubed: this is made evident by lining the Tube with sheet Lead for then every time the outer surface is excited a Spark may be drawn either from the Lining or from the rubed surface; but when taken from one no more appears on the other till the Tube be excited anew. The Electric fire being driven out on one surface when it is accumulated on the other appears similar to the appearances in charging the Lyden Bottle, but there is this difference that when the surcharge on either side of the Tube is taken off the remaining electrical fire is restored to its natural state in the glass, which happens in Charging the Bottle only when the surcharge is taken from that Surface to which it was immediately communicated by the Prime Conductor; when taken from the other the surcharge still remains on the first. Perhaps these appearances may be of use for discovering the causes of the different effects of Globes which are solid having but one surface, and of those which are hollow. I intend as soon as the Weather is suitable to repeat your Experiments and if any thing arises worth notice I shall take the liberty of communicateing it to you. I am affraid that by a long delay of acknowledging the receipt of your Letter it might appear that I had not a due sence of the honour you do me, a continuance of which I shall gladly endeavour to make agreable to you, perhaps this has led me now to trouble you too triflingly; I hope the intention will plead my excuse.
Endorsed: Copy of Letter to Benjm Franklin August 12th 1756
7. This letter is identified in Colden Paps., V, 88–9, as being from Cadwallader Colden. The MS is in David’s hand, however, and the deferential tone is that of a younger man to an elder, quite unlike that which his father customarily used in letters to BF.