From John Perkins
ALS and AL: American Philosophical Society5
Boston Octobr. 23d 1752
In the Inclos’d you have all I have to say of that Matter. It prov’d longer than I expected so that I was forced to ad a Cover to it. I confess it looks like a Dispute but that is quite contrary to my Intention. The Sincerity of Friendship and Esteem were my motives nor do I doubt your scrupling the goodness of the Intention. However I must confess I cannot tell exactly how far I was acted by hopes of better Information in discovering the whole Foundation of My Opinion, which indeed is but an Opinion, as I am very much at a loss about the validity of the Reasons. I have not been able to differ from you in Sentiment concerning any thing else in Your Suppositions. In the present Case I lye open to Conviction and shall be the gainer when inform’d. If I am right you will know that without my adding any more. Too much said on a meerly Speculative matter is but a Robbery commited on practical Knowledge. Perhaps I am too much pleas’d with these dry Notions. However by this you will see that I think it unreasonable to give you more trouble about them than your Leisure and Inclination may prompt you to. I am Sir Your oblidged Humble [Servant]
Postscript. On the 21t Instant early in the morning died Dr. W. Douglas of an Apoplectic Fit. He left a large Estate and one Child which he acknowledged as his own Son; but has not adopted him, nor after deligent Search do we yet hear of any Will.6
Addressed: For Mr. Franklin Post-Master Philadelphia
Endorsed: Dr Perkins
Since my last7 I consider’d that as I had begun with the reasons of my Dissatisfaction about the ascent of Water in Spouts You would not be unwilling to hear the Whole I have to say and then you will know what I rely upon.
What occasion’d my thinking all Spouts descend is that I found some did certainly do so. A difficulty appeard concerning the ascent of so heavy a Body as Water by any Force I was apprised of as probably sufficient. And above all a view of Mr. Stuarts Portraits of Spouts in Phil. Trans.8
Some Observations on these last will include the chief Part of my Difficulties.
Mr. Stuart has given us the Figures of a Number observ’d by him in the Mediterranean All with some Particulars which make for my Opinion, if well drawn.
The great Spattering which relators mention in the Water where the Spout descends And which appears in all his Draughts I conceive to be occasiond by Drops descending very thick And large into the Place.
On the place of this Spattering arises the Appearance of a Bush into the Center of which the Spout comes down. This Bush I take to be form’d by a Spray made by the force of these Drops which being uncommonly Large and descending with unusual Force by a Stream of Wind descending from the Cloud with Them increases the height of the Spray which Wind being repulsed by the Surface of the Waters rebounds and Spreads; by the first raising the Spray higher than otherwise it would goe; and by the last making the Top of the Bush appear to bend outwards (i.e.) the Cloud of Spray is forced off from the Trunk of the Spout and falls backward.
The Bush dos the same where there is no appearance of a Spout reaching it And is depress’d in the middle where the Spout is expected. This I imagin to be from numerous Drops of the Spout falling into it together with the Wind I mention by their descent which bent back the rising Spray in the Center.
This Circumstance of the Bush bending outwards at the Top seems not to agree with what I call a Direct Whirlwind but consistent with the revers’d: For a Direct one would sweep the Bush inwards; if in that Case any thing of a Bush would appear.
The Pillar of water as they call it from its likeness I suppose to be only the End of the Spout immers’d in the Bush a little blaken’d by this additional Cloud and perhaps appears to the Eye beyond its real bigness by a refraction in the Bush and which Refraction may be the cause of the appearance of Seperation betwixt the part in the Bush and that above it. The part in the Bush is Cylindrical as ’tis above (i.e.) the bigness the Same from the Top of the Bush to the Water. Instead of this Shape, in Case of a Whirlwind it must have been Pyramidal.
Another Thing remarkable is the Curve in some of them. This is easy to conceive in Case of descending Parcels of Drops through various winds, at least till the Cloud condenses so fast as to come down as it were Uno rivo: But it is harder to me to conceive it in the ascent of Water that it should be convey’d along, Secure of not leaking or often droping through the under Side in the prone part. And Should the water be convey’d So Swiftly and with such force up into the Cloud as to prevent this, it would by a natural disposition to move on in a present Direction presently Straiten the Curve raising the Shoulder very Swiftly till lost in the Cloud.
Over every one of Stuart’s Figures I see a Cloud: I suppose his Clouds were first, and then the Spout; I dont know whether it be so with all Spouts, but Suppose it is. Now if Whirlwinds carry’d up the Water I Should expect them in fair weather but not under a Cloud; as is observable of whirlwinds. They come in fair Weather, not under the Shade of a Cloud, nor in the Night since Shade cools the Air. But on the contrary violent Winds often descend from the Clouds; Strong Gusts which occupy Small Spaces; and from the higher Regions extensive Hurricanes &c.
Another Thing is the appearance of the Spout coming from the Cloud. This I cant account for on the notion of a Direct Spout. But in the real descending one it is easy. I take it that the Cloud begins first of all to pour out drops at that particular Spot or Foramen. And when that current of Drops increases So as to force down wind and vapour the Spout becomes so far as that goes Opaque. I take it that no Clouds drop Spouts but such as make very fast and happen to condense in a particular Spot which perhaps is coldest and gives a determination downwards so as to make a passage through the Subjacent Atmosphear.
If Spouts ascend it is to carry up the warm rarified Air below, to let down all and any that is colder above: And if so they must carry it through the Cloud they go into (for that is cold and dense I imagin) perhaps far into the high Region making a wonderfull appearance at a convenient Distance to Observe it, by the Swift rise of a body of vapour above the region of the Clouds. But as this has never been Observ’d in any Age, if it be supposable thats all.
I cannot learn by Mariners that any Wind blows towards a Spout more than any other way but it blows towards a Whirlwind to a large Distance round.
I Suppose there has been no Instance of the water of a Spout being Salt when comeing across any vessel at Sea. I Suppose too that there have been no Salt Rains. These would make the Case clear.
I suppose it is from some unhappy Effects of these Dangerous Creatures of Nature that Sailors have a universal dread on them of breaking in their Decks should they come across them.
I imagin Spouts in cold Seasons as Gordon’s in the Downs prove the descent.9
Quere Whether there is not always more or less Cloud first where a Spout appears.
Whether they are not generally on the Borders of Trade-Winds And whether this is for or against me.
Whether there be any credible Account of a Whirlwind carrying up all the Water in a Pool or Small Pond. And when Shoal and the Banks low a Strong Gust might be Supposed to blow it all out.
Whether a Violent Tornado of a Small Extent and other Sudden and Strong Gusts be not Winds from Above descending nearly perpendicular. And whether many that are call’d Whirl-Winds at Sea are any other than these, and so might be call’d Air Spouts, if they were Objects of Sight.
I overlook’d in its proper Place Stuart’s No. 11 which is curious for its Inequalitys, And in particular the Approach to breaking which if it would not be too tedious I would have observed a little upon in my own way as I think this would argue against the Ascent &c. but I must pass it not only for the reason mention’d but want of Room, besides.
As to Mr. Stuarts Ocular demonstration of the Ascent in his Great perpendicular Spout the only one it appear’d in I say as to this what I have written Supposes him mistaken Which yet I am far from asserting.
The Force of an Airy Vortex having less Influence on the Solid Drops of Water than on the interspers’d cloudy Vapours makes the last whirl round Swifter tho it descend Slower. And this might easily deceive without great Care the most unprejudiced Person.1
5. The letter (except its postscript) and the enclosure are printed as Letter XIX in the 1769 and 1774 editions of Exper. and Obser. A few words, illegible in the MSS, have been silently supplied from the printed texts. No significant differences exist between MS and printed versions, though the latter are correctly punctuated and therefore easier to read and comprehend. Both papers were read in the Royal Society, June 24, 1756.
6. Douglass (see above, p. 336 n) died intestate, leaving a large house in Green Dragon Lane and personal property valued at £3185, to be divided between his nephew and sister. Nathaniel B. Shurtleff, A Topographical and Historical Description of Boston (Boston, 1871), p. 610. The child referred to may be the boy, born 1745, whose education Douglass undertook and to whom he gave his name. Douglass, A Summary, Historical and Political, of the … British Settlements in North-America (London, 1760), II, 346–8.
7. See above, p. 358.
8. Alexander Stuart, “Part of a Letter … concerning some Spouts he observed in the Mediterranean,” Phil. Trans., XXIII (1702–03), 1077–82, with an illustrative plate.
9. Rev. Mr. Patrick Gordon, “Part of a Letter … concerning a Waterspout observed in the Downs,” Phil. Trans., XXII (1700–01), 805–6.
1. Following this document in the Franklin Papers in APS is a single sheet in an unknown hand, headed “Extract from a Voyage which seems to have been made in the Year 851 by a Mohammedan,” which contains a one-paragraph description of water spouts in the Indian Ocean.