Richmond July 10th 1820
I duly received your verry obliging favour of the 22d of may last I am truly sorry to be informed of the State of your health, which I hope is better. In my communication of the 11th of that month I had no sort of expectation that had your health permitted that you would that time engage in Meteological subjects. This communication was to call your attention as you are the only writer that I have had the pleasure of perusing who has attended to this climate in Such a manner as to exhibit a Table. This is a Science of recent date. I find that it is much practised in Eaurope There is Greate diversity in the quantity of water which falls in the different parts of the Globe according to these tables. I also find that the winds without the tropicts no where prevail as they have done at this place for these two or three years (Say between east and South) I hope that you will pardon the Suggestion of keeping a Register at the New College and altho I make no doubt but that Should Such a design be in Contemplation the necessary apparatus will fixed, yet I will Suggest a convenient method of ascertaining the quantey of Rain This may be done by a cistern of metal Say Tin, cased with a cistern of wood lined with metal so as to leave a Space between these cisterns of about two inches the inner cistern should have a cover to fit tight to which a neck Should be fixed about three feet in length* on the top of which a funnel to any proportionate Size of the cistern. being constructed with a flat bottom, the top and bottom of equal Size. in this a float with a Rod to pass through the neck of the cover into the funnel which is intended to receive the Rain; this Rod to have feet inches and line marked on it in such a way as to Shew by examination the quantity of Rain which may fall in any required time: These cisterns should be placed in the earth and the better to Secure whatever debth it may be constructed. the top of the cistern to which the pike thro which the foat Rod is intended to pass Should be about three feet below the surface of the earth and the Space dug out to receive it about one foot deeper and one foot longer in than the cistern, and in placing the cistern, one foot of clay well puddled should be made at bottom and the cistern placed in the center on this puddle when it is about half Settled or Shrunk. It will be then of a consistance hard wrought to sustain the weight of the cistern it will then Stand out, and this Should Should be placed over the cistern on the Surface of weight Sufficient to Sustain the cistern in its place, while the Shell Round the cistern is puddled up to the Top . This puddle when dry will protect the cistern from decay (tho the outer be of wood) and protect it from the changes of the humidity of the earth the distances on the Rod attached to the float be graduated to the proportion of the mouth of the funnel with that of the cistern. an apparatus thus fixed will Shew the exact quantity of Rain that fall in any Givin time, the base trouble as the water can be pumped out, to any particular gage, at any time, should the suggestion be worthy of your attention I will with pleasure send you a drawing of this Apparatus. The vaporating cistern is a thing with which I am told Greate care Should be taken. Should institution conclude on keeping a Meteorological Register the other fixtures Such as the Barometer Thermometer and vane can be easily obtained. the latter has I find been So fixed as to shew on a dial plate in any Room of a house over which it is placed the course of the currant of air without attending to the vane itselfe. There is a remark which is common among those who I have conversed, who have observed the Barometer in America and Eaurope particularly, Britain that the canges in the atmosphere do not Affect it in the Same proportion in America as there; I find that one writer Mr Copland to the Royal Society in the year 1793 Says that one thing is certain with that Instrument that heat and cold in all climates. I find from a Meteorological Register kept at Calcutta in the year 1784 that of the Termometer was 70° and that of the Barometer about 30 That their fell 81 inches of Rain at that place . At or near Edinbrough in the year 1776 about 29 inches in the year 1792 there fell on the western coast of Greate Britain about 47 inches The medium of Rany days at Paris for a number of years is 126. the quantity of Rain about 20 inches each year, thus it will be found that in the Climate of paris, the mean quantity of Rain is in the proportion of one fourth the quantity at Calcutta thus the organization of matter proceeds with time in their Several ordinations in perfect harmony without regard to the minute which have come under our observations. I formerly mentioned that from your Statement that the quantity of Rain at that place or its kneighbourhood was about 47 inches. The quantity If we calculated the Small Streams is reduced, in years in the proportion as 60 is to 100. This can only be accounted for from drawing a comparison Between the quanty of Rain which fell previous to the decrease of those Streams and their present Supply of water and other matters worthy of a Serious investigation. In the consideration of this subject three things present themselves first that the quantity of Rain is less, Secon’d. that the Absorption or that the exelation is Greater or that each Combine to this fact, we must of necessity conclude; To ascertain the former is now made the Subject of this communication This can be ascertained by the Simplest capacity by Being previously provided with a Suitable apparatus. The subject of exelation is a matter which in my humble oppinion requires absttration it will be found that the quantity of exelation is Greater in proportion than the quantity of Rain, which falls this Seems to be admitted wherever Meteological observations have been made, These lead us to the enquiry whether there is not a proportion such vessels as these trials have been made or Whether the night dew supply the difference I have not from the Limited opportunity I have had of research been able to make any calculation. If a digression is proper I Shall endevour to Give you my crude Ideas on that Subject by caling to view the Observations of Doctor Hallie on the current wich makes from the Atlantick in to the Mediterrannean Sea This Greate man after having exhausted his Genius, has concluded by endeavouring to account for it by exelation. his process is familiar to you; I shall confine my observations within the Small limits of my research he has endeavoured to account for this current on the principals of evaporation others by a counter current below the Surface. The latter by the curveture of a Suspended cord below the Surface this is of all others the most absurd, for in all waters the particles Glide in proportion to their distance from the Surface, and it will ever be found that the curveture of a line thus Suspended will be in the proportion of its Size the Suspending weight and the motion of the current* with due diffidence to the former I take the liberty to offer to your It is my oppinion from the best information I have been able to Obtain that this is caused from absorbsion There being Such a portion of Africa a Sandy desert and a certain district whereon rain never falls.†I have atributed the current to that cause I merely make these Suggestions to you for consideration There is one other Subject of Some moment to this State that is now under execution that is a correct Map of the State. It is a verry deserable object How fare this will be obtained in the present attemp I cannot Say, withe certainty. I am inclined to believe that too much is required for the Sum apropiated of this I can only judge from my own litle experience I have sometime pased published a Map of the city merely from compilation this cost but a Small Sum I have A Map of this city including Manchester and the jurisdiction of the city drawn from Actual Survey The angels taken by one of Geborts most improved Theodilites and all the distances measured horizontal This on a scale of 400 feet to an inch will require Six Sheets This works has occupied three or four years of my time and it will cost from four to five thousand dollar to have it ingraved printed Shaded and mounted The limited demand for this Map requires the Subscription to come high from a comparison I cannot believe that a correct Map of this State can be made for the Sum contemplated in addition I have substantial reasons to believe that the undertaker of this work is by no means qualifyed for this undertaking hower well he may understand Mathematicks his vision is defective and all his facters are thoretical I have the most Statifactory evidence that he is no Surveyor, According this law it was contemplated to lay down the latitude and Longitude of each court house in the State all the most remarkable mountains by celestial observations like wise their height the latter could be easily accomplished With a Good Barometer this Should all ways where practicable by Triangles taken from a correctly measured Base this is the foundation of all calculations and a long experience has taught me that it requires not only time but Greate attention to measure correctly. Triangles are hard to be correctly obtained among Mountains The Barometer must when they cannot be correctly obtained be depended on An instrument such as to correctly take the angles of the havenly body’s So as to lay down the latitude and Longitude of the places required would cost considerable and the transportation and fixing up at these places would require time and considerable expence greate advantage is often derived by having two persons both for Observation and Calculation I am by no means quallifyed to say what it would cost to comply with this what I understand was Contemplated by the Legislature. but I cannot believe that three times the sum apropiated woud have been more than Sufficient with the most Strict eoconomy, I cannot pretend to the united wisdom of the Legislature but without due submission it was to be expected that the period between the passage of this law and the time the contract was entered into was Sufficient, to enable them to examine the Subject with more Scouting than when this law was enacted. A Map of the State was a most desirable object to accomplish which I fear that the apropiation will be Spent without Otaining any part of the Object This in the event that the new Map Should not be found more correct than that published by Mr Maddison and others, that it will not on the whole I am well Satisfied for while it may correct Some errours, it is likely to leade us into more and I had Suggested a more Simple method of obtaining a Map which tho it woud have cost considerably more than contemplated It have been as correct as the nature of things at this time would require. This by ascertaining the true latitude of the capitol and exstending intersecting lines at given distances across the State at distance these accurately measured would be the best correction on the Surveys of counties and if correctly measured any inacessiable distances could be taken by means of Rockets by haveing an observer at each end of the Base line.*all the work could by this means be brought neare enough of to correctness for the present mean of the State and a Greate-deal of Local matter could have been obtained by way of key to the work tho not as copious as contemplated by this work It is but natural for us to be partial to our own Suggestions and therefore I am a verry improper Jude whether it is not likely to obtain a more corret Map on this plan than is likely to be obtained for the means by the method proposed, errours by these means can be comitied by the other it will require a connection by a Series of Angles some of the plans inaccessiable to the Sight even by Rocketts the latter mithod would require more labours the former will be attended with Greate difficulty and if not done with the Greates accuracy confusion will be the result I am Satisfied that the most skillfull Geographer Astronomer and Survey could not Say what Sum it would require to make a Survey and map of each county as contemplated by the Act of assemby by many thousand dollars it would So fare exceed his calculations. every necessary precaution, and eoconmy used both in time and expence much depends on the Skill and exertions of the principal Surveyor who Shoud allways have the Assistance of capables persons to assist him in chaining perambulating observeing noteing and calculating two at least is necessary for the latter When I get my map of Richmond published I will Send you one and the key which is intended to accompany it I am Shure you will be much Surpriseed to find that the Jurisdiction line line of this city is upwards of 23 miles, longer than Paris or London The paper Towns which Surround this city has nearly evaporated its inhabitantse The Streets as named by you when you were a director of Publick buildings have been retained and the number added within the Jurisdiction had nearly exhausted my powers to find apropiate names as you will See when you get this map the publication of which is protracted on account of the common Hall not having Subscribed towards it publication all the respectable inhabitance who are intrested have Subscribed but a work of this kind local as it now will need the aid of this city before it can go under the hand of the Engravers The Map the key and the plate are ready the former for the Engravers and the latter for the Printers the Greate depression here is beyond example If we take into view that we have neither been visited with the ellements fire or water without our controll or desire they are of a penuary nature ariseing mostly from the examples and designs of some of our most infuencal citizens whos Ambition led them into wild and extravagant speculation in Lots Lands Tobacco and Flour and other things these have been failure to a greate exstent by the Banks the example of these individuals have had a most lamentable effect on the Scociety here I have had more amediate knowledge of the former as my profession led me to lay of a vas many Section of land for Sale. I often attended these sales and as often witnessed the Grocers, the Blacksmith the Shoemaker Carpenter Bricklayer even the Night watch become land speculators, this by way of Geting rich as some few had done by the rise of property which according to the prevailing oppinion was never to obtain its medium in accounting to come These follys were the effects of certain leading individuals to which the many look up to as samples the old habits of industry are too slow for their purpose Those habits of Industry and frugality are insipped in comparison with imaginary wealth of which we supposed ourselves all these have have been fostered by the leading individuals in Scociety I fear it has had its influence in our publick councils most of the Chartered companys in this place have been managed in such a manner as to defeat the design for which they were granted making them a total loss of capital to the Stockholders Experience points out the necessity of more circumspection in granting charters to companys their Objects should be well defined before they are granted their real objects have been kept behind the Sceen until Alarmed and there are the means of Ruin to many. I most sincerely have to ask your indugence in detaining you so long on subjects the only motive I can have for writing is that if you can obtain any thing from them which you can make usefull to Scociety, they are at your service I am in the meantime
DLC: Papers of Thomas Jefferson.