I had the honor of your favor of the 23d Ultimo. by Mr Barnes, whose short stay here prevented me from enjoying the gratification of shewing such attentions as I could wish, independent of your friendly recommendation, to which I shall at all times be exceedingly happy to pay particular respect.—Though I believe he is not unfavourably impressed with the Situation & appearance of our new City, yet I am afraid he will think the difficulty of obtaining a sufficient number of houses greater than he perhaps was previously led to imagine.—This inconvenience will however only be temporary, for very great exertions are making on all sides. I am much obliged by your kindness in suggesting several important considerations respecting the Arrangements in the Capitol & I have the satisfaction of informing you that they are so nearly consonant to my Plans that what I had directed will I flatter myself meet with your approbation.—There is however a difference in the Closet which will be on one side of the Room, from necessity. It will give me very great pleasure to have the honor of your Company when you return from Philaa. & if you make any stay I solicit that favor, at which time you will be so good as to aid by further Advice. Though much has been done here we still appear in the infancy of our operations & your improved Mind would suggest many things worthy of our attention.—

In writing to you I cannot omit a subject which has long been deeply impressed on my mind & to you this will be interesting not only as the President of the Philosophical Society but as a Philanthropist:—I mean that subject of National Affliction the Yellow Fever; on the production of which I entertain many of the opinions of the ingenious & benevolent Dr Rush, tho’ I am not a friend to copious bleeding but would Recommend a reduction of the fever by perspiration produced by the Warm bath, & evacuations, making use of tonics in the latter Stages of the Disease.—The Yellow fever is thought by many to be imported from the West Indies—It may be the Case, but the Type only could by importation be given, the predisposition at least must be generated in the city where it prevails Philaa.—If the fever originates in the West Indies, or in Africa we must enquire into the Causes? and what Causes can we find in those countries that are unknown in our populous Cities? We have in the Summer, Heat, Moisture, frequently a stagnant Air, stagnant Water & its consequent Pests; but in many of our Cities we have Causes which cannot be exceeded in the cities even of Africa.—In Philaa. and other places the inhabitants in preparing their Privies sink very deep Receptacles which in many cases have not been cleansed in thirty or forty years—These are frequently in very confined yards, & if we calculate the number of these Pits of abomination, & their diameter which is often very large, taking also into consideration how much vapor rises from an acre of ground in a given time:—If we likewise reflect on the quality of this vapour, which is generated not only by the feculent Matter but also by the leaves of Cabbages and other vegetable Offals thrown there especially in the late summer-Months, we need not search for remote or proximate causes.—Perhaps it may be objected that Philada. & other Cities which have lately experienced such calamities have not annually been afflicted by this Disease, & yet the same causes existed.—We know that at various times different parts of this Continent have been subject to similar disorders among the Aborigines as well as their Successors the Whites—Causes, not now generally contemplated might aid the production of putrid fevers previous to the establishment of the White inhabitants. The Indians more actuated by present motives than consequences might have placed their towns in unhealthy Situations & their filthy modes of Life would contribute to give Effect to the noxious exhalations.—We know likewise that in Revolutions of the heavenly bodies relative Situations or Aspects produce Effects on the different Planets to which common Observers do not attend—We learn from the Chaldeans that their discoveries enabled them not from calculation but from mere observation to foretell Eclipses and the changes of Season dependent on the Saros or great Cycle. Modern Philosophers have matured Systems derived from these Observations & have been able to predict the Seasons with tolerable Accuracy—The Seasons whether humid or dry depending on great primary celestial Movements give us reason to imagine that a concomitance of Circumstances is required to produce the Effects under present contemplation; & may not these account for the absence or presence of our general Disorders?—But destroy any of the requisite Agents and the Effect ceases.—Whatever may be the primary, it is certainly reasonable to endeavour to lessen the exciting causes, and we possess the full power of removing what we suppose to be one great agent: I mean the effluvium of which I have spoken above.—During the sitting of the Grand Convention at Philada. our amiable and enlightened friend Madison, who lodged in the same house with me, asked what I thought was the best mode of correcting the effluvium. I observed the Servants preparing Ley (a lixivium of Wood Ashes) for making Soap, & some lime Waggons going bye at the same time, I told him the Materials were at hand & he should witness the immediate effect.—I threw some quick lime into the Ley, & when it was slaked & mixed, the whole, (then become a caustic Alkali) was thrown into the Reservoir of the Privy; & no sooner had it mixed with the fæculent matter, than the vapour was changed & rendered innoxious & without the least smell.—This very simple operation need not be repeated oftener than once in two or three weeks & so small a quantity is requisite that neither the expence nor trouble can be considered.—Some put only lime into their Privies but it produces a Volatile pungent Vapor, still very disagreeable; the fixed Alkali is also requisite. If quick lime & fresh Ashes were thrown into every Reservoir at stated times, by persons appointed by the Magistrates & not depend upon the inhabitants whose negligence might be fatal, & if this were to become a matter of police supported by a very small Tax I hesitate not to say that it would be more effectual in preventing disease than if the River Delaware were to be distributed thro’ the City—I am nevertheless an advocate for the System of watering now in progression.—

There are various other considerations which I must mention as inducements to this Scheme.—As the Abolishment of error is deemed a benefit to Science, so may the Removal of a nuisance be considered as an acquisition to comfort. It matters not to what the attention is directed if we contemplate Utility.—The Almighty has, in his Providence, ordained, that no natural Evil is without its Remedy. The flies of Philada. are considered as one of the greatest of Nuisances & the Origin of such Myriads has excited many Enquiries & many false conclusions.—They follow and torment Horses so much that people in general think they breed in the dung of these Animals.—Flies are the Scavengers of Nature, & wherever there is offensive Animal Matter they deposit their Eggs, & the maggots devour the putrid Mass; for the substances non-appropriate are seldom chosen. The dung of horses dries without corrupting, unless laid in heaps; when, like other vegetable Matters, it ferments & in time decays, but not with the noxious fætor of animal Substances. We accordingly find that flies do not deposit their Ova in the Dung of horses, but they are often seen to suck the fresh juices of this Substance as well as the blood of the Animal.—When I exhibited the effects of Quick Lime & Alkali in completely correcting the disagreeable Effluvium that arises from the Privies I observed the whole surface of the fæculent Matter to be alive with Maggots, which at once convinced me of the Origin of such a number of flies, & I shuddered at the Idea. Although convinced myself it was necessary nevertheless to make an experiment to convince others. After leaving the door & Windows of a privy open for some time, and perceiving the maggots to be very numerous, I ordered it to be kept constantly shut, & the flies that came forth were in such numbers that every day for some time hundreds or thousands of dead ones were brushed from the floor, which died for want of water & Sustenance; shewg1 that although putrid animal Matter is proper food for maggots, yet it is not fit for the sustenance of flies. The fæculent Matter was not replenished by the flies it produced, & at last it became destitute of Maggots.—The mixture of Quick lime & Ashes or Ley not only destroys the Smell, arising from the Sewers, but also effectually destroys the Maggots & consequently the flies.—It may be observed that when Persons are afflicted with the Yellow fever the putrid bilious matter which is vomited in the last Stages & all the noxious matters otherwise discharged by the Body, are thrown into the general reservoir of filth & infection, which no doubt would tend essentially to increase & propagate the Fever: all these however would be rendered innoxious by the mixture Recommended, besides which the nightmen, by it, will find no inconvenience in cleansing the Sewers; & this Operation being facilitated will not only tend much to purify the City, but the matter itself will be rendered by the mixture much more valuable, not only as a manure, whose nature is changed, & which greatly exceeds in quality the common Matter, but will serve a still more valuable purpose, as it becomes a perfect Matrix of Nitre, formed of the requisite ingredients for the production of that Substance in the most compleat Manner.—

On all these Accounts therefore I cannot forbear requesting your attention to this Subject.—Not only from respect & love to the inhabitants of Philaa. but as a citizen of the United States & still more as a man I think it my duty to make known whatever I conceive may, in any respect, tend to their good, and I cannot commit my Ideas to a bosom that will Participate more in the Wish of promoting the general good than in yours.

Accept dear Sir my high Respect & sincere good Wishes for your health & happiness