'If any invencion which I set you aboute, take effect, you shall have a share in the benefitt arising from it.
'If you come to my lodging at mornings, evenings, or any other times of your best leisure, and doe for me such small things as I have to doe either every day or but once in 2 or 3 dayes, as your, my affaires, doe fall out, you shall not loose your labour.
'In briefe, all the end that I have in you for myselfe, is to have a friend whom I may trust and who is handy, neere about mee. If by God's providence you can find out any way whereby you may advance yourselfe better than by having any dealing with mee, I shall promote you therein, and bee heartily glad of the occasion.
'If you please to come upon these tearmes (which in good faith are best, and the best hopes I am able to give you) let mee know it. If I prosper in my wayes, you shall feel it. I onely desire that you would bee cordiall and true to mee, without labouring to circumvent mee, and I shall be as willing to doe for you as you are for yourselfe.
'You were best to bring you a bed and such things else with you as may bee of use to you here.'
Although the copying-machine had only secured a doubtful success, it made Hartlib and his friends look to the inventor to show himself to the world 'by some rare piece or other;'[1] and, together with the publication of his 'Thoughts on Education,' it greatly extended Petty's acquaintance among the leading scientific and literary men of the time in England. In 1646, with Hartlib and Boyle, he became a member of the 'London Philosophical Society.' This club had been inaugurated in the previous year by Theodore Haak, a German from the Palatinate, and comprised amongst the members the already well-know names of Dr. Wallis and Dr. Wilkins. In 1649 Petty resolved to follow their example, and remove to Oxford,[2] where Wilkins had just been appointed Warden of Wadham.
The city had surrendered to the Parliamentary army on June 24, 1646, and the University was soon after reorganised
