Thanks hm--us. Reproduced here:
Additional dictionary entries for BE: it's not in the OALD, Cambridge, Macmillan. Collins lists it as 'obsolete', OED lists as 'now rare'.
immission in British
(ɪˈmɪʃən) or immittance (ɪˈmɪtəns)
the act of inserting something
a. The action of immitting; insertion, injection, admission, introduction. The opposite of emission.
1578 J. Banister Hist. Man viii. f. 102 The strife therof [‘how the sight is made’] as yet is vnder iudgement, as touchyng emission, and immission.
1612 J. Selden in M. Drayton Poly-olbion x. Illustr. 165 The Northwinde (much accounted of among builders..for immission of pure ayre).
1651 Bp. J. Taylor XXVIII Serm. xxii. 281 God does not give immissions and miracles from heaven to no purpose.
1713 W. Derham Physico-theol. i. i. 5 After such frequent Compressures, and immission of fresh Air.
1856 D. Masson Wordsworth in Ess. 349 The..theory of..alternate immission and withdrawal of power, as regulating the progress of the universe.