20 LETTERS ON SCIENTIFIC SUBJECTS. 



DR. JOHN DEE TO CHARLES JACKMAN AND 

 ARTHUR PETT. 



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



Instructions for the two masters, Charles Jackman and Arthur 

 Petty geven and delyvered to them, at the Court day holden 

 at the Moschovy house, the \*Jth of May, anno 1580, with 

 which instructions a new charte (made by hand) was geven 

 allso to eche of the sayd two Masters, expressing their Cathay 

 voyage more exactly then any other yet published. 



In the name of Jesus ! 



Yf we reck en from Wardhouse to Colgoyeve Hand 400 

 myles, for allmost 20 degrees difference, only of longitude, 

 very nere east and west, and abowt the latitude of 70. 



And from Colgoyeve to Vaygatz 200 myles, for 10 degrees 

 difference (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 shortest 

 distance betwene which two is allso east and west, in the la- 

 titude likewise of 70) are 1200 myles. Then is summa totalis 

 from Wardhouse to Tabin, 600 leages or 1800 myles Eng- 

 lish. 



Therefore allowing in a discovery voyage, for one day with 

 an other, but 50 myles English ; yt is evident that from 

 Wardhouse to Tabin, the course may be sayled easily in 36 

 dayes. But by God^s help, it may be fynisshed in much 

 shorter tyme : both by help of wynde prosperous, and lyght 

 continuall 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 farder 

 easterly, it is probable that you shall fynde the lande on your 

 right hand, running much sowtherly and eastward, in which 

 course you are like either to fall into the mowth of the famous 

 ryver Oechardes, or some other : which (yet) I conjecture, to 

 pas by the renowned City of Cambalu : and that mouth to 

 be in the latitude abowt 50 or 52 degrees, and within 300 or 

 400 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 work 

 entitled Pierces Supererogation, 4to. Lond. 1593, p. 190. William Bourne also, 

 in his Inventions or Devises, Lond. 1578, p. 17, makes honourable mention of him 

 as an inventor. A mathematical-instrument-maker of the same name, living 

 " neere unto the North dore " of St. Paul's, is mentioned by Worsop in his work 

 entitled Discoverie of sundrie errors and faults daily committed by Lande-meaters, 

 4to, Loud. 1582; t>ut I am uncertain whether this latter notice refers to the same 

 person. 



