Receiver (air pump)
Two pictures of a "receiver" (Boyle, 1660), which comprises parts A, the vacuum bulb, the screw in cap at the top, and the bottom "male" connecting part, which fits into the vacuum pump R. The one at the left has a string inside, used e.g. to ring a bell, the one on the right has a fish in water inside, so to test what happens to a fish in a vacuum. [2]
In science, receiver, refers to a type of vacuum bulb, of an air pump, e.g. a Boyle air pump (1659), that is able to “receive” or have thing put into it, though a generally 4-inch opening in the top, e.g. candles, birds, fish, bells, etc., then sealed, so that classical doctrines about what can and cannot occur in a vacuum can be tested.

Quotes
The following are related quotes:

“Apart from any new features that were special to the pumps or valves, Hooke's machine contained three design features that were of the greatest significance. The first of these was a large glass vessel some 15-inches in diameter, called the 'receiver', which contained the space to be evacuated. Secondly, a brass stopper some four inches in diameter set and cemented into the top of the glass receiver made it possible to gain easy access to the experimental area, and seal everything up before the pumper set to work. Thirdly, an ingenious secondary brass stopper with conical sides passed through the large stopper, so that when liberally coated with salad oil, it could be turned around without breaking the air seal. This rotating stopper could be used to pull a thread to actuate some experiment in vacuo. With Hooke's machine, therefore, the experimenter had easy physical access to a fairly large experimental site that was entirely visible through the thick walls of the glass Receiver. It was to be used to conduct a series of experiments which needed clear vision and the ability to ignite and move things.”
— Allan Chapman (2004), England’s Leonardo (pg. 24) [1]

References
1. Chapman, Allan. (2004). England’s Leonardo: Robert Hooke and the Seventeenth-Century Scientific Revolution (Greatorex, pgs. 23, 272; receiver, pg. 24). CRC Press.
2. (a) Boyle, Robert. (1774). The Works of the Honorable Robert Boyle, Volume One (editor: Thomas Birch) (air pump photo, pg. end matter). A. Millar.
(b) Shapin, Steven; Schaffer, Simon. (1985). Leviathan and the Air Pump: Hobbes, Boyle, and the Experimental Life [fish in receiver cover (ΡΊ) edition]. Princeton, 2011.

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