Tennis balls used as a measure, 1580

A playster for an ague 

Take as much stone pitch to the value of a Tennis bal, and a spoonefull of Tarre, and a penniworth of Treacle and Rosen, to the value of a Tennis ball, and a spoonefull of Hony, boyle it over the fier in a little kettle, and stirre it all togeather till it be well melted, then take a new sheapes skinne, and make holes in it with a bodkin, and spreade the medicine on the fleshye side of the skinne, and lay it to the ache as whot as you may.

An Hospitall for the Diseased, by T C, London 1580

Rosen would be resin, and 'whot' is 'hot'. 'Value' here is presumably used to mean 'size' or 'weight', since the monetary value of what is being measured is explicit - ' a penniworth of treacle and rosen'. This is the earliest example I have come across of an item of specifically sports equipment being used as a non-metaphorical referent outside the field of sport - it's not uncommon to see distances measured by lances or arrows, which would have been used as sporting items, but they are primarily weapons. There's an assumption too in the reference that people dispensing medicine would have a good idea of the size and weight of a tennis ball.

For sinews that be broken in two

Take Wormes while they be knite, and looke that they departe not, and stamp them, and laye it to the sore, and it will knit the sinewes that be broken in two.
from The Good Huswife's Jewell, 1596

There's a mixture here of the doctrine of signatures and curiously possible viable medicine. The worms would be earthworms, 'knite' - that is knitted together, or mating. The instructions say that you must pulverise them before they separate. The intention here is to use two things which are more often separate, but at certain times come together. Mash them and you catch their 'essence of togetherness'. Current research in the west indicates that earthworms have antibacterial properties, though whether these would help to knit together torn sinews is not known. But certainly pulverised earthworm was a much-used ingredient in early modern western medicine, and is still used in the east. A sad end for them in this case, though following the established literary pattern of the lovers united in death.