w below in
order to increase the force and velocity, take in the air, and make the
resistance as great as may be required. These, too, should be of light
material and of sufficient size; they should be in the shape of birds'
wings, or the sails of a windmill, or some such shape, and should be
tilted obliquely upwards, and made so as to collapse on the upward
stroke and expand on the downward. Fourth, place a balance or beam
below, hanging down perpendicularly for some distance with a small
weight attached to its end, pendent exactly in line with the centre of
gravity; the longer this beam is, the lighter must it be, for it must
have the same proportion as the well-known vectis or steel-yard. This
would serve to restore the balance of the machine if it should lean over
to any of the four sides. Fifthly, the wings would perhaps have greater
force, so as to increase the resistance and make the flight easier, if
a hood or shield were placed over them, as is the case with certain
insects. Sixthly, when the sails are expanded so as to occupy a great
surface and much air, with a balance keeping them horizontal, only a
small force would be needed to move the machine back and forth in a
circle, and up and down. And, after it has gained momentum to move
slowly upwards, a slight movement and an even bearing would keep it
balanced in the air and would determine its direction at will.'

The only point in this worthy of any note is the first device for
maintaining stability automatically--Swedenborg certainly scored a point
there. For the rest, his theory was but theory, incapable of being put
to practice--he does not appear to have made any attempt at advance
beyond the mere suggestion.

Some ten years before his time the state of knowledge with regard to
flying in Europe was demonstrated by an order granted by the King of
Portugal to Friar Lourenzo de Guzman, who claimed to have invented a
flying machine capable of actual flight. The order stated that 'In
order to encourage the suppliant to apply himself with zeal toward
the improvement of the new machine, which is capable of producing the
effects mentioned by him, I grant unto him the first vacant place in
my College of Barcelos or Santarem, and the first professorship of
mathematics in my University of Coimbra, with the annual pension of
600,000 reis during his life.--Lisbon, 17th of March, 1709.'

What happened to Guzman when the non-existence of the machine was
discovered is