A Further Account of a New Machine, Called the Marine Surveyor, Designed for the Mensuration of the Way of a Ship at Sea, More Correctly Than by the Log, at Present in Use, or Any Other Method Hitherto Invented for That Purpose. By Mr. Henry De Saumarez, of the Island of Guernsey, Part of His Majesty's Antient Dutchy of Normandy

Time dissolving the grosser Salts, and fitting them to be carried off through the Urinary Passages. These Waters have been found of excellent Avail in many other Illnesses, besides the Scurvy and Evil: But I forbear mentioning any other Cases, lest I trespass against good Manners, by making my first Visit too long. I am with all due Respect, SIR, Your very humble and obedient Servant, Holt, Dec. 16. 1728. John Lewis. III. A further Account of a new Machine, called the Marine Surveyor, designed for the Measurement of the Way of a Ship at Sea, more correctly than by the Log, at present in Use, or any other Method hitherto invented for that Purpose. By Mr. Henry de Saumarez, of the Island of Guernsey, Part of his Majesty's antient Duchy of Normandy. HAVING given an Account of my Projection for ascertaining the Run of a Ship at Sea, which has appeared in the Philosophical Transactions of the Royal Society, Vol. xxxiii, for the Months of November and December 1725; as also in those for the Months of March and April 1726; and having been since frequently employed in making Experiments thereof, and Improvements thereon, I take Leave to add what follows as a Supplement to those Discourses on this Invention, which I am humbly of Opinion may, in Time, prove of great Use in those extensive Branches of our foreign Commerce, wherein so many of his Majesty's Subjects are concerned. At my publickly setting out on this Invention, I had his late Majesty's Leave several Times to have a Boat on the Canal in St. James's Park, where the Shalowness of the Water was such, that it would not admit of my using the Iron Fork, the Weight of which may be about four Pounds, and which I have described in the Transactions afore-mentioned; and therefore I was obliged to fall on some Expedient to answer my Purpose in such a Depth of Water. Various were my Designs to this End; however at length I fixed such a Machine to my Boat, as had an equal Number of Revolutions in a measured Distance of 2000 Feet, even though the Boat went swift or slow; of which the Reverend Dr. Desaguliers, and some other Mathematicians, at Times, were Witness. As I did not describe this Instrument in the former Account of my Machine, where it seems to lie blended with that of the Fork, I shall give a Description of it here in the following Figures, viz. In the First of these Figures, F represents my Boat on the Canal in St. James's Park, through the Rudder of which a small Spindle passes (in an Iron Pipe) of which HG is the Length. To the Point G are fastened the four Iron Fins, or Flyers, A, B, C and D, in the Form of a Square, the Bars DB and AC, to which they are fixed, lying in an horizontal Position. These Flyers are so contrived as to have full Play in any Motion of the Boat. To the Point H, which is the upper Part of the Pipe and Spindle, is fixed the Dial E: Now the Boat being put into Motion, the Flyers move accordingly, which proportionally affecting the Spindle, the Motion is thereby communicated to the Dial, which may be fitted to strike the Miles or Leagues that the Vessel runs. But to describe the first Movement of this Machine more exactly, Fig. 2. represents it unfixed. The Cross, or Bars DB and AC, as I said before, lie flat, or in an horizontal Position; the Arbor or Spindle, which is perpendicular thereto, screws into the Point G, and passes through an Iron Pipe to the Dial, in manner aforesaid. The Flyers A, B, C and D being fitted to move in any Motion of the Boat, the Bars are accordingly affected. This Instrument is so contrived, that two of the Flyers on one Side shall always resist the Water in the Motion of the Vessel, whilst the other Two give Way in their Turning. The resisting Flyers in this Figure are A and B, and D and C will be the same when they come into their Position; for they resist and give Way alternately so long as the Motion continues, which is always circular; and so truly does it revolve, that be the Motion swift or slow, in any measured Distance, the Number of Revolutions will be equal. This is the Machine which I first tried on the Canal in St. James's Park, and with this it was, that I made my Observations on the Tides in the River Thames, as they appear in the Philosophical Transactions for the Months of March and April 1726; which I chose the rather to do, in regard I found it to answer very well in all my Experiments. And I am yet of Opinion, that it would be an useful Instrument to determine the Strength of the Tides on our Sea Coast, which if marked in our Charts, might prove advantageous to our Commerce. But considering, that though this Projection might be serviceable in Barges, Pleasure-Boats, or other Vessels, in fair and moderate Gales of Wind, yet it might prove useless in boisterous and stormy Weather, and in long Voyages, when it might be choaked with Weeds; I therefore fixed to my other Invention the Fork, which is contrived in such a Manner, that I will even yet be so bold as to affirm, it shall determine the Ship's Way in a Storm, or when she is scudding before the Wind, when the Log is incapable of it. As the Canal would not allow me to try, with any Certainty, my Iron Forks there, I was obliged to have some made of lighter Materials, which seemed to answer somewhat near the Truth, and made me so sanguine as to believe, that they would have an equal Number of Revolutions in the same Distance, even though the Motion of the Boat was swift or slow between Mark and Mark. I must here do my worthy Friend Dr. Desaguliers (who frequently honoured me with his Company in the Experiments of the aforesaid aforesaid Invention) the Justice to own, that he dis- sented from me in this Particular, in regard he said the Forks must have different Positions, according to the Velocity of the Vessel to which they were fixed, and consequently could not have an equal Number of Re- volutions in swift and slow Motion. Whilst I was considering where to carry on my Experiments to prove the Verity of my Instrument, and to answer this Objection, I had the Honour to be introduced to the late ingenious Samuel Moly- neux, Esq; whose Memory will always remain dear to me. As he was ever ready to encourage all lau- dable Designs, and particularly such as were calcu- lated for Publick Good, he soon became my Patron: And as he was then one of the Lords Commissioners of the Admiralty, and my Machine fell within his Province, he express'd a Desire to see an Experiment of it on the River Thames: Accordingly I shew'd to him, and several of the principal Officers and Com- missioners of his Majesty's Navy, the Nature and Use of it between London and Woolwich, when he seemed to be of the same Opinion with Dr. Desa- guliers, viz. Whether in a certain Distance, and in different Motions of the Vessel, the Instrument could revolve equally. Hereupon he advised me to take a Trip over to Holland, and to try my Machine with the Log, in my Passage; as also throughly to examine the Truth of his Objection on the long Canals in that Country, where there was little or no Tide or Current. Accordingly I had Orders to embark on Board the William and Mary Yacht, which was ordered to carry over the Lady of Count Welderen, one of the then Dutch Ambassadors at our Court, to compliment his Majesty on his Accession to the Throne. My Machine being fixed at the Stern of this Vessel, we kept her Run both by it and the Log. On the nicest Calculation, in our Passage over, the Difference between us was 2 Miles and 2640 Feet: At this I was in no wise surprised; for as I knew the Log to be very erroneous, and I undertook to correct the Errors of it by my Instrument (in the Truth of which I might then be too forward, as too many are on such Occasions) I was assured we could not agree; and therefore I charged the Difference accordingly. Among the considerable Company on board the Yacht, we had a curious Gentleman, Captain Lynslager, Commander of one of the Dutch Men of War, who seemed not a little pleased with my Contrivance; and no sooner did he land in Holland, but he spoke of it to some Gentlemen of the highest Rank there, whose Curiosity induced them to desire to see an Experiment of this Invention: Accordingly I was sent for to the Hague, and on the Canal there, before Baron Hop, Baron Wassenaar, Admiral Somelsdyk, Mr. s'Gravesand (Professor of the Mathematicks in the University of Leyden) Captain Lynslager, &c., we run a certain Distance in swift and slow Motion, in order to see if the Instrument would have an equal Number of Revolutions therein. In running up, it revolv'd 2300 Times, and in coming down 2060. Here then was enough to convince me, that Dr. Desaguliers, and Mr. Molyneux, had judged truly of the Fork, and more especially since the learned Mr. s'Gravesand joined in Opinion with them; them; who notwithstanding encouraged me, by telling me my Labour was not in vain, for that the Instrument might still be of good Service, by making Tables to rectify the different Revolutions. An Opinion strongly indulged is rarely parted with; the Truth of which I find in myself; for although Dr. Desaguliers, Mr. Molyneux, and Mr. s'Gravesand did jointly agree as to this Invention, yet still did I entertain some slender Thoughts, that it must answer the Purpose, in the Manner I had proposed. For when I considered, that I had two Fathom of Rope out on the Dutch Canal, which was but 5 or 6 Feet deep, and that the Fork of my Machine weighed about three Pounds, or three and a half, and was two Feet and a half in Length, I thought it not unreasonable to suppose, that its Weight, in the slowest Motion of the Vessel, might occasion it to strike Ground, and consequently impede its Motion, and lessen the Number of Revolutions as above. Of this I had been fully satisfied whilst in Holland; but fearing to lose my Passage in the Yacht, on Board of which I had embarked by Order of the Lords Commissioners of the Admiralty, I was obliged to hasten over. Not long after I came to England died my worthy Patron Mr. Molyneux, in whom all Men of Learning and Ingenuity lost a Friend; and as there was now but little Hope of my going over to Holland in the Manner I had done before, I was notwithstanding resolved to take that Journey at my own Expence; and accordingly did so, where I no sooner began my Experiments, but I was convinced of the Truth of the Objections of the three learned learned Gentlemen afore-mentioned, which is plainly made appear from the following Figure, wherein the Position of the Fork, in five different Motions of the Vessel, is represented. See Fig. 3. This needs no Explanation, for it plainly appears, that the Pallets will be more or less affected by the Resistance of the Water, according to the Position they are in; and therefore the Revolutions in a swift or slow Motion, in the same Distance, cannot be equal. Being now fully persuaded, that the Fork would not revolve equally in the same Distance, and in different Motions of the Vessel, I now began to repair this Defect by calculating some Tables, which render it still a very useful Instrument. On what Foundation I formed these Tables, there will be no need for me to mention, since I shall go on to shew what further Improvements I have made of this Instrument, and that it is now every Way useful without them. And this, I think, I cannot better do, than by entering here the Extract of a Letter to Dr. Desaguliers from a learned Mathematician in Holland, whose Company I was honoured with several Times, whilst I was making my Experiments on that Side, viz. "Mr. De Saumarez having desired me to acquaint you of the Success of the Experiments, which I have seen him make of this Machine, for the measuring the Way of a Ship in the Sea, it is with Pleasure I undertake it, since I am fully persuaded you will not be wanting to contribute all in your Power to promote an Invention so useful and advantageous as this is. "The "The first Experiment that I attended was with an Iron Fork, such as the Gentleman himself hath described in the Philosophical Transactions of the Royal Society; when the Number of Revolutions were more in the swift than in the slow Motion of the Boat, whereon we tried this Instrument. This I take to be owing to the different Inclinations of the Machine; which were more Horizontal, according as the Motion of the Boat was more swift; from whence we concluded, that it would be necessary to help this by some Tables calculated for the Purpose: Since which, Mr. De Saumarez hath accordingly formed such Tables; but as I was not present at the Experiments wherein they are founded, I leave you to the Gentleman himself to give you an Account thereof. I have also made another Experiment with Mr. De Saumarez, upon a new Correction of his Machine, which he will better explain to you, when you see him, than I can describe. Here he has contrived the first Movement of his Machine to lie Horizontal under the Water; and such was our Success in this Experiment, that I make no more doubt of the Usefulness of this Invention, which I look upon as very advantageous to Navigation; since the Number of Revolutions here scarcely differed 4 in 332 in the different Velocity or Motion of the Boat: But this I must observe, that the Number of Revolutions here were greater when we moved most slow. For my Part, I do not question, but that by a small Correction, the Number of Revolutions may be always rendered proportional to the Distance; yet let us make no Hypo- "Hypotheses; for Experiments of this Machine, wherein may be had some Millions of its Revolu- tions, will perfectly shew the Use that may be made thereof. In the Interim I believe, that Mr. De Saumarez's Invention may be, nay, ought to be, especially with this last Improvement, infinitely preferred to all other Methods for ascertaining the Way of a Ship in the Sea, &c. Here then you have the Opinion of a learned Gen- tleman of my Improvement on this Invention, whose Eminence among the Literati is such, that this alone might give a Sanction thereto. It is here observed, that the Difference in the Revolutions of my Ma- chine, on this new Method, was scarcely $\frac{4}{332}$: Who then can say this Difference was not owing to the different Sheers in our Boat on the Canal? But I shall not go about to determine this, it remains for me now only to shew the Improvement which I made of the Marine Surveyor whilst in Holland, which is hinted at in the Letter above, and which is now brought to such Perfection, that I persuade my self no very material Objections can be brought against it. The following Figure shews this Improve- ment, wherein the Objections of the different Incli- nations of the Fork are now entirely removed. See Fig. 4. A F G H is the Fork, in the same Form as the Iron Fork described in the Philosophical Trans- actions, Vol. xxxiii, for the Months of November and December 1725, which differs from the other only in the Materials of which it is framed; this be- ing contrived of such as to make it equiponderous with the Water, and to lie in an Horizontal Po- sition, fition, even though the Ship or Vessel to which it is fastened be at Anchor, or under Sail. HB is a Rope, of a convenient Length, fixed to a Screw or Worm at the Point B, which goes about 6 Inches into an Iron Pipe, of which BI is the Length: Through this Pipe an Iron Spindle passes into the aforesaid Screw or Worm to which the Dial C is fixed; as soon then as the Vessel moves, the Fork plays in an Horizontal Position, which moving the Spindle within the Iron Pipe, the Motion is thereby communicated to the Dial, which is fitted to strike to the Miles or Leagues the Vessel runs; and let the Vessel move swift or slow, the Pallets A and F are equally affected, and consequently must measure the Distance failed to a greater Exactness than the Iron Fork is capable of in the Manner I have described it in the Philosophical Transactions aforesaid. For want of better Conveniencies when in Holland, I had this Iron Pipe fixed to a thin Board, which I fastened to the Rudder of the Vessel DE; but as I am now falling on a proper Method to fix this Iron Pipe, &c. which I could not well do in Holland, since the cold Weather was so far set in, that it would not allow me to make more Experiments than I did on that Side, I hope soon to make it appear, that the Revolutions are exactly equal in this new Improvement of the Fork. Here then do I offer what I humbly conceive cannot fail being of Service to the Community of which I am a Member, as well as to all the Maritime Powers. 'Tis the Fruit of several Years Study; for my Thoughts were first employed on it, when the Nation felt so great a Loss as it did in the unhappy Fate Fate of Sir Cloude's Shovel, &c. since which Time (from the Numbers of Workmen I have employed, the various Alterations I have made, and the great Variety of Experiments carried on at my own sole Cost and Charges) I have been at no small Expence; insomuch that my Estate has felt the Weight thereof. However, it is some Satisfaction to me, that I have brought it to the Pitch it is now at, where I cou'd wish to see the Publick take it up, and have it tried by competent Judges against the Log, the Errors of which I have amply set forth in a former Discourse. This, methinks, is what I might reasonably hope for, since, as I set out with honest Views, in a praise-worthy Undertaking, I ought (to use the Words of a considerable Author on this Head) to meet with Assistance in the Beginning, with Encouragement if I succeed, and even with Pity, if not Praise, although I should fail. I am well aware, that he who decries an old Custom, seldom meets with Success, even though what he advances against it may be very reasonable. This seems to be the Case between the Marine Surveyor and the Log; for the latter having been long in Use amongst the Seamen, it may be with Difficulty the former will be received; which probably I may not live to see, since, as I am now bending beneath the Weight of Age and many Infirmities, I cannot be far off bidding Adieu to the Things of this World; and when I shall make my Exit from it, God grant some happy Genius may raise a good Structure on the Ground-work which I have here marked out: And I am the more earnest in this Wish, because I am firmly of Opinion, that that what is here advanced, if rightly conducted, cannot fail of proving highly advantageous to Trade and Navigation. January 23d, 1728-9. Henry de Saumarez. POSTSCRIPT. In a former Discourse on this Invention, and which appears in the xxxiii\textsuperscript{d} Volume of the Philosophical Transactions, I hinted that I was upon making a further Improvement in Navigation, whereby I proposed to make a Ship work far better to Windward, than it is possible for the most Weatherly one to do at present; as also to make them tack and ware in much less Room than is generally done on such Occasions. The Advantages arising from such a Projection, if it proves practicable, must be considerable; for 1. The Ship which is in Danger of a Lee-Shore will hereby be enabled to weather the Point she may want, and not be forced, in stormy Weather, to anchor in the very Breach of the Shore, and even in the Jaws of Destruction. Of this we have had too many melancholy Instances, where several Lives and Fortunes have been lost; Disasters of which kind, it is humbly conceived, may, in a great Measure, be prevented by this Invention. 2. Hence we need not fear to get the Weathergage of an Enemy; for by plying to Windward much faster than he can, and by tacking and waring in much less Compass, I can either leave him, or continue to engage him, as shall appear most convenient: At least I can so spend the Day, as to be able to secure myself under the Covert of the Night; or if I chance to be near the Land, I may hereby be enabled to gain a safe Harbour. 3. By this Invention the wild Steerage which is too frequently made in some Ships, will be prevented, which all Mariners must allow to be of Service, especially in chasing, or being chased by an Enemy; as well as in their keeping the Reckoning of the Ship's Way, &c. I might here touch on other Advantages arising from this Project, which I omit at present, since as I am about preparing some small Models to shew the Nature of this Contrivance, they will fully appear therefrom: And if what I offer should not be so practicable in large Ships, as it were to be wished, I yet hope some happy Genius will, in Time, so far improve on what I shall hint, as to make the same serviceable to my Country. When I consider, that to Navigation Great Britain owes its Riches and Strength, it certainly ought to have the Preference to all other Arts and Sciences; and therefore any Improvement therein surely cannot fail of meeting with Regard; more especially where such desirable Ends are proposed, as a Method to prevent Ships being wreck'd on Lee-Shores, as also a Means to facilitate the Escape of them, when too powerfully attacked by an Enemy; or leading them to Victory, where they have any Prospect of it, &c. As hereby Honour may accrue to the Nation, and the Lives and Fortunes of several People may be saved, I only desire publick Experiments may be made of these my Machines, on the Proof of which I am willing to stand or fall. H. D. S. IV. A