For those of you who have not read the Pre WW1 Files from 1900 to 1913 you may perhaps not know how to work in 'LS' units as regularly mentioned in those files. It would be a pity were you to miss out these files for they are packed to the limit with interesting detail of the beginnings of the W/T Branch in the Royal Navy. However, if you look at the 1913 page and then scroll down to the 'Aerial Flown From Kites.pdf' section you will see the formula in a worked example - there are many other incidences of these worked examples from 1900 to 1913 files.

The LS of a circuit is the tuned circuit represented by capacitance and inductance [L and C] and the resultant circuit is resonant to a specific frequency. The formula is

wavelength in feet = 206 √LS

so, when the text tells you that a range of waves is from 11LS to 50LS it means

wavelength in feet = 206 x 3.317 {this is the square root of 11} = 683.3 feet x 12 [to bring it to inches] = 8199.62 " 39.3 [to bring it to metres] = 208.64 meters = FROM 1.437 MHz

repeat that for 50 LS =  TO 670 kHz.

Meters, remember, are converted to MHz or parts of a MegaHertz by dividing 300 [a derivation for the speed of light = velocity]  by the number of meters e.g. 300 meters = 1 MHz, or 30 meters = 10 MHz, and 650 meters would be 0.461 MHz or 461 kHz etc.

Look at this file to understand how it was done at around the time of the First World War Receiving Model MB.pdf