“ tude by the lunar motions. I presume therefore it will not answer. accept my affectionate salutations.”

On May 14 Lewis wrote to Jefferson from Philadelphia: “In your instructions to me you mention that the instruments for ascertaining by celestial observations the geography of the country through which I shall pass, have been already provided: I shall not therefore purchase any articles on that discription untill I hear further from you on this subject. Will you be so good as to inform me what instruments have been provided? and where they are?--it may be possible that some instrument has been omitted, which M ^r. Patterson, M ^r. Ellicott and those gentlemen to whom you have referred me in this place, may deem necessary for me, and if so the deficiency can be supplyed in time.--

"M ^r. Patterson and M ^r. Ellicott both disapprove of the Theodolite as applicable to my purposes; they think it a delicate instrument, difficult of transportation, and one that would be very liable to get out of order; they also state that in it’s application to any observations for obtaining the Longitude, it would be liable to many objections and to much more inacuracy than the Sextant--The instruments these gentlemen recommend, and which indeed they think indispensibly necessary, are, two Sextants, (one of which, must be constructed for the back observation), an artificial Horizon or two; a good Arnald’s watch or Chronometer, a Surveyor’s Compass with a ball and socket and two pole chain, and a set of plotting instruments.--By means of the Sextant fixed for the back observation and an artificial Horizon also constructed for the purpose; the meridian altitude of the Sun may always be taken, altho it should even exceed eighty degrees: for this valuable problem I am indebted to M ^r. Patterson.--

"As a perfect knolege of the time will be of the first importance in all my Astronomical observations, it is necessary that the time-keeper intended for this expedition should be put in the best possible order, if therefore Sir, one has been procured for me, and you are not perfectly assured of her being in good order, it would be best perhaps to send her to me by some safe hand, (should any such conveyance offer in time); M ^r. Voit could then clean her, and M ^r. Ellicott has promised to regulate her, which, I believe he has the means of doing just now, more perfectly than it can be done any where else in the UStates.--

"I cannot yet say what day it will be in my power to leave this place.--Your different orders have been attended to, and the result you shall have in a day or two.”

Jefferson answered this from Washington on May 16: “ yours of the 14 ^th. is this moment recieved, & I hasten to answer it by return of post, that no time may be lost. the copy of instructions sent you are only a rough draught for consideration. they will not be signed or dated till your departure. presuming you would procure all the necessary instruments at Philadelphia, which is a principal object of your journey there, the instructions say that the necessary instruments ‘ have been provided’, which will be true when they recieve their ultimate form, date & signature, tho’ nothing was provided at the time of writing the rough draught. this will serve to correct the impression which has been misunderstood, and to let you know you are relied on to provide every thing for yourself.--with respect to the Theodolite, I wish you to be governed entirely by the advice of m ( ^~ r) Patterson & m( ^~ r) Ellicott. as also as to the time piece & whatever else they think best. m( ^~ r) Garnett told us he had some good ones still on hand; which I remind you of, lest you should not be able to get one in Philadelphia. accept my affectionate salutations. ”

On May 29, Lewis wrote to say that he would be ready to leave Washington on June 6 or 7 and that he had done Jefferson’s shopping as requested in his letter of April 23: “I have at length so far succeeded in making the necessary preparations for my intended journey as to be enabled to fix on the sixth or seventh of June as the probable time of my departure for Washington. All the article [ sic -- Ed. ] have been either procured, or are in such state of forwardness in the hands of the workmen as to induce me to to M ^r. Gallatin, that I have not been able to procure Danvill’s map--The maps attatched to Vancouver’s voyage cannot be procured seperately from that work, which is both too costly, and too weighty, for me either to purchase or carry.--”