Another closely connected problem is that of locating or ascertaining the direction of the sending station.
It is still very valuable as a help in ascertaining the principles of ancient music, and gives us the opinions of some of the best ancient writers on the art.
In 1853 exhaustive experiments were carried out in England with a view to ascertaining whether it would be possible so to treat alcohol as to allow it to be used industrially without, at the same time, any risk of the revenue being defrauded.
He constructed a map of as many as 576 of these lines, the principal of which he denoted by the letters of the alphabet from A to G; and by ascertaining their refractive indices he determined that their relative positions are constant, whether in spectra produced by the direct rays of the sun, or by the reflected light of the moon and planets.
A much better approximation to the heat of combustion of such substances is obtained by deducting the oxygen together with the amount of carbon necessary to form C02, and then ascertaining the amount of heat produced by the residual carbon and hydrogen.