A recent Portuguese postage stamp of interest to philatelists and navigators alike was issued to commemorate the fiftieth anniversary of an adventurous air flight over the Atlantic from Portugal to Brazil by two officers of the Portuguese Navy, Rear-Admiral Cago Coutinho and Commander Sacadura Cabral.

In a valuable memoir published in English as well as in Portuguese by the Club Militar Naval of Lisbon an account of the novel method of navigation adopted by the two aviators is given. In the foreword to the memoir we are told:

‘The use of points of reference through the line of the intended crossing, and the able and skilful modifications of the formulae of nautical astronomy, by which the observer may, before starting, prepare the greater part of his calculations, in this way leaving only another quite material [small] part to be done in the air, are the two original conceptions by which the astronomical navigation, with a sextant, can be done in the air with accuracy and comfort …’