page no 425 note on * Some Recent Developments in Aircraft Instruments, by Major H. E. Wimperis, M.A., F.R.Ae.S.

page no 427 note on * On the assumption of a uniform lapse rate θ = θ₁ – σh

where θ₁=ground temperature, absolute.

θ = absolute temperature at a height h metres.

σ=lapse rate in degrees per metre.

It can be shown that

P/P₀ = {(θ₁ – σh)/θ₁}l/c_σ.

where P₀=ground pressure.

P₀ = pressure at height h metres.

c =a constant.

Using the data 1 cu-cm of air at a pressure of 1013.2 m.b. in latitude 45 (g=980.62) weighs 0.001247 gms. at a temperature of 10° C. the value of c is found to be 27.278.

This formula is the general formula for any ground temperature and any lapse rate. The S.T.Ae., or as it is now called, the I.C.A.N. Convention, is calculated as shown; the lapse rate chosen is that shown by such a line as F G (Figure 00), i.e., a lapse rate of 6.5° C. per kilometre, but the ground temperature is taken as 15° C, i.e., 288 absolute.

This gives the formula P/P₀ = {(288-.0065 h)/288}5-256.

page no 429 note on * It can be shown that if H be the “ isothermal height ” and h the “ lapse rate height ” at the same pressure then the two heights are connected by the equation

where θ₁ = ground temperature, absolute, from which the lapse rate begins.

θ₀ = constant temperature absolute of the isothermal height.

σ = lapse rate.

Inserting the lapse rate of 1.98 C. per 1,000 feet of lapse rate height and the value of θ₀ as 283, the formula becomes

page no 435 note on * Journal of the Optical Society of America and Review of Scientific Instruments, March, 1926.

page no 443 note on * J. H. Jellett, Dublin Trans. R. Irish Acad., Vol. 22 (1855),

page no 444 note on * The Equations of Equilibrium of an Elastic Plate Under Normal Pressure, Phil. Mag., January, 1922, p. 97.

page no 455 note on * Journal of the Optical Society of America and Review of Scientific Instruments, March, 1926.