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LETTERS ON SCIENTIFIC SCBJECTS.

DR. JOHN DEE TO CHARLES JACKMAN ANDARTHUR PETT.

[MS. Lansd. No. 122, Art. 5. Orig.]

Instructions for the two masters, Charles Jackman and ArthurPett, geven and delivered to them, at the Court day holdenat the Moschovy house, the 17 lh of May, anno 1580, with•which instructions a new charte (made by hand) ivas gevenallso to eche of the sayd tioo Masters, expressing their Cathay voyage more exactly then any other yet published.

In the name of Jesus !

Yf we reckon from Wardhouse to Colgoyeve Hand 400myles, for allmost 20 degrees difference, only of longitude,very nere east and west, and abowt the latitude of 70§.

And from Colgoyeve to Yaygatz 200 myles, for 10 degreesdifference (only in longitude) at 70 degrees of latitude allso.

And from Vaygatz to the promontory Tabin, being 60 de-grees different in longitude; (the whole course or shortestdistance betwene which two is allso east and west, in the la-titude likewise of 70) are 1200 myles. Then is summa totalisfrom Wardhouse to Tabin, 600 leages or 1800 myles Eng­ lish .

Therefore allowing in a discovery voyage, for one day withan other, but 50 myles English ; yt is evident that fromWardhouse to Tabin, the course may be saylcd easily in 36dayes. But by God ’s help, it may be fynisshed in muchshorter tyme : both by help of wynde prosperous, and lyghteontinuall for the tyme requisite thereto.

When you are past Tabin, or come to the longitude of 142(as your charte sheweth) or 2, 3, 4, or 5 degrees fardereasterly, it is probable that you shall fynde the lande on yourright hand, running much sowtherly and eastward, in whichcourse you are like either to fall into the mowth of the famousryver Oechardes, or some other: which (yet) I conjecture, topas by the renowned City of Cambalu: and that mouth tobe in the latitude abowt 50 or 52 degrees, and within 300 or400 myles of Cambalu, ytself being in latitude abowt 45 de-

thematical Jewel in the British Museum , mentions “old Humphrie Cole” as a“ mathematical mechanician” ; and he applies the same term to him in his workentitled Pierces Supererogation , 4to. Loud. 1593, p. 190. William Bourne also,in his Inventions or Devises , Lund. 1578, p. 17, makes honourable mention of himas an inventor. A mathematieal-instrument-maker of the same name, living“ neere unto the North dore” of St. Paul’s, is mentioned by Worsop in his workentitled Discoverie of sundrie errors and faults daily committed by Lande-meaters,4 to, Loud. 1582; but I am uncertain whether this latter notice refers to the sameperson.