If it were possible to measure accurately the true bearing of the sun or star at the moment of observation, then a single observation of a single heavenly body would fix the position of the craft at the intersection of the line of bearing with the position line. At the time of writing, however, there are no satisfactory means of making such a measurement with the required degree of accuracy. Apparatus which will enable this to be done is now in course of development. Navigation by means of astronomical observation will thereby be simplified greatly. NAVIGATION BY WIRELESS DIRECTION FINDER With the great improvements that have been made in the year 1919, the guiding of aircraft by directional wireless telegraphy is rapidly becoming a reliable and accurate means of aërial navigation. Although complicated in design and construction, the complete receiving equipment for aircraft is now light, compact, and simple of operation. [Illustration: HOT COFFEE WAS TAKEN ABOARD] [Illustration: SLOW RISING NEARLY CAUSED DISASTER AT THE START OF THE GREAT FLIGHT] The receiving equipment on aëroplanes and airships is arranged so as to indicate, with a comparatively high degree of accuracy, the direction from which wireless signals are received. The position of the sending, or beacon, station being known, the bearing of the aircraft from that station may be plotted on a suitable chart, in which small segments of great circles are represented by straight lines. Simultaneous bearings on two known beacon stations are sufficient to fix the observer's position with tolerable accuracy at the intersection of the lines of bearing, provided that they intersect at a reasonable angle--45 degrees or more, where possible. With the very close tuning rendered possible by the use of continuous waves, beacon stations of the future will probably be provided with automatic means whereby directional signals can be sent out at intervals of one hour or less. Such signals will be coded, so that the crews of aircraft can identify the wireless station. The wave lengths must be chosen so as not to interfere with messages sent from commercial stations. If there be a beacon station at the air navigator's destination, it is possible for him to direct his course so that the craft is always headed for the beacon; and in due time he will reach his objective. This simple but lazy method, however, is not to be recommended; for, owing to the action of the wind, the route covered is longer than the straight course. To counteract drift and proceed in a direct line towards his destination, the air navigator frequently has to direct his course so that the craft is not headed straight for the objective. Hence, with a single beacon station, frequent observations of drift are necessary, if the shortest route is to be followed. Thus: [Illustration: Approximate path taken by aircraft headed always towards beacon station.]