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A Flexible Catheter

To John Franklin

Dear Brother Philada. Dec. 8. 1752

Reflecting yesterday on your Desire to have a flexible Catheter, a Thought struck into my Mind how one might possibly be made: And lest you should not readily conceive it by any Description of mine, I went immediately to the Silversmith’s, and gave Directions for making one, (sitting by ’till it was finish’d), that it might be ready for this Post. But now it is done I have some Apprehensions that it may be too large to be easy: if so, a Silversmith can easily make it less, by twisting it on a smaller Wire, and putting a smaller Pipe to the End, if the Pipe be really necessary. This Machine may either be cover’d with a small fine Gut first clean’d and soak’d a Night in a Solution of Alum and Salt in Water, then rubb’d dry which will preserve it longer from Putrefaction: then wet again, and drawn on, and ty’d to the Pipes at each End where little Hollows are made for the Thread to bind in and the Surface greas’d: Or perhaps it may be used without the Gut, having only a little Tallow rubb’d over it, to smooth it and fill the Joints. I think it is as flexible as could be expected in a thing of the kind, and I imagine will readily comply with the Turns of the Passage, yet has Stiffness enough to be protruded; if not, the enclos’d Wire may be us’d to stiffen the hinder Part of the Pipe while the fore Part is push’d forward; and as it proceeds the Wire may be gradually withdrawn. The Tube is of such a Nature, that when you have Occasion to withdraw it its Diameter will lessen, whereby it will move more easily. It is also a kind of Scrue, and may be both withdrawn and introduc’d by turning. Experience is necessary for the right using of all new Tools or Instruments, and that will perhaps suggest some Improvements to this Instrument as well as better direct the Manner of Using it.

I have read Whytt on Lime Water. You desire my Thoughts on what he says. But what can I say? He relates Facts and Experiments; and they must be allow’d good, if not contradicted by other Facts and Experiments. May not one guess by holding Lime Water some time in one’s Mouth, whether it is likely to injure the Bladder?

I know not what to advise, either as to the Injection, or the Operation. I can only pray God to direct you for the best, and to grant Success.

I am, my dear Brother Yours most affectionately

I find Whytt’s Experiments are approv’d and recommended by Dr. Mead.