The eigenfunctions i/̂ n) are similar to the set Bv(psp)defined by Tranter [28]. The chief difference is that thei/̂ "' are true cylinder functions with all their desirable fea-tures, whereas the Bv are not (composed of Bessel func-tions, but coefficients depend on order v [23]). A virtue ofthe Bv is their orthogonality for all v, whereas the i/4n) areorthogonal only for n = 0, 1 and 2. The latter is sufficientfor the coaxial symmetry treated here. Further, the il/{"]

may readily be generalised. For example, consider thefamiliar coaxial-cavity resonance condition

with roots psN [23], which generalises eqn. 11 to ordersN > 1. We define the eigenfunction set that correspond-ingly extends eqn. 13:

<Mn|N) = {Jn(psNP)YN(PSNa) - Yn(psNpVuiPsna)}/NsN (35)

JNipp)YN{pa) - a) = 0 (34)

These are cylinder functions re the order n, and oneverifies exactly the same properties as eqns. 24-29 withthree minor changes: the added index N; Jt -*• JN in eqn.25 and eqn. 28; and orthogonality eqn. 29 now forn = N - 1, N, N + 1. Note that, while the ^ n ) used inthis paper correspond to the special case N = 1, theBv(psp) correspond to the degenerate case i^v|v).

ErrataCHEUNG, A.Y.: 'Microwave hyperthermia for cancertherapy', IEE Proc. A, 1987,134, (6), pp. 493-522

The authors wish to delete the previous acknowl-edgement to Ms. Jenan Al-Atrash as she is, in fact, thecoauthor. However, both authors would like to acknowl-edge the assistance of Mr. Ali Neyzari.

5807A

ALLEN, N.L.: 'Corona, breakdown and humidity in therod-plane gap', IEE Proc. A, 1986,133, (8), pp. 562-568

The author is grateful to Mr. Robert Lanoie of the Insti-tut de Recherche d'Hydro-Quebec, Varennes, CanadaJOL 2P0, for drawing attention to some errors in theabove paper. These relate to the definition and use of theterms 'humidity correction factor' and 'humidity coeffi-cient'. Discussion with Mr. Lanoie suggests that properconsistency is obtained by making the following changes:

(a) Eqn. 1 becomes:

100(1)

with the following change three lines later '. . . IEC[4],and Kh is the humidity correction factor and e the humid-ity correction coefficient (per cent per g/m3).'

(b) In Fig. 1, the ordinate is Kh only and is dimension-less.

(c) Following the change made in eqn. 1, Kh becomes ein Figs. 2, 3 and 4.

(d) The equations after eqn. 2 should read

„ , h - Ktd

100

and Kh ~ { 1 -h-h std

100(3)

With these changes, greater precision of definition and ofconsistency with the IEC document are achieved.

5819A

IEE PROCEEDINGS, Vol. 134, Pt. A, No. 10, DECEMBER 1987 767