IMPROVEMENTS IN OR APPLICABLE TO PROJECTILES
Year: 1878

page_text: LETTERS PATENT to Alexander Charles Mac Leod, of Yockleton Hall, in the
County of Salop, Doctor of Medicine, for the Invention of "IMPROVEMENTS IN
OR APPLICABLE TO PROJECTILES."
Sealed the 4th February 1879, and dated the 8th August 1878.
PROVISIONAL SPECIFICATION left by the said Alexander Charles Mac Leod
at the Office of the Commissioners of Patents on the 8th August 1878.
ALEXANDER CHARLES MAC LEOD, of Yockleton Hall, in the County of Salop,
Doctor of Medicine. "IMPROVEMENTS IN OR APPLICABLE TO PROJECTILES."
My Invention consists of an elongated projectile, having internal passages or
channels rectilinear and parallel with one another, but at an angle with the long axis
of the projectile, and by preference tapering to the posterior end, permitting through
themselves the free passage of the atmospheric air. And this projectile is further
provided with a contrivance at its posterior end in the manner of a valve, made of
india-rubber or other elastic material, or of a combination of materials, which con-
trivance hermetically closes the posterior end of the projectile, preventing the entry
or escape of any portion of the explosive gas during the passage of the projectile
through the barrel. Immediately however on the projectile quitting the barrel the
valve is forced off by the opposing air, which, entering the aforesaid passages or
channels, communicates to the projectile a spinning or rotary motion on its longer
axis.
This projectile is adapted for both cannon and small arms, and though specially
intended for smooth or unrifled barrels may also be advantageously used for rifled
barrels.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Charles Mac Leod in the Great Seal Patent Office on the
8th February 1879.
ALEXANDER CHARLES MAC LEOD, of Yockleton Hall, in the County of Salop,
Doctor of Medicine. "IMPROVEMENTS IN OR APPLICABLE TO PROJECTILES."
Many projectiles have been devised with the object that they should rotate or
spin when fired from a smooth barrel, as does an ordinary elongated bullet when
fired from a rifled barrel. For this purpose spiral or twisted grooves or channels
have been made either on the external surfaces or in the interiors of such projectiles.
It has been supposed that the action of the explosive gas, or of this gas and the
atmospheric air together on these spiral grooves or channels would produce the
desired spinning motion. But it was impossible that any such devices should have
succeeded, for the reason that the tendency of the explosive gas being to rotate such
a projectile in one direction, the tendency of the atmospheric air is to rotate it in a
direction exactly opposite or reverse! So that such a projectile in the first part of
its course would spin or rotate, say, to the right, and in the second part of its course
to the left, that is, if it did rotate at all a second time.
A projectile to rotate in the manner desired should be grooved or channeled in
one of three ways.
Firstly, There may be two distinct sets of grooves, such as are shewn in Figure 1
of the annexed Drawings, one set on the anterior aspect of a projectile for the air
to act upon, and another set, but inclined in an opposite or reversed direction, for
the explosive gas to act upon.
Secondly. The projectile may be grooved and constructed as represented in
Figure 2, so that the explosive gas alone shall enter and act upon such grooving.
Or, Thirdly. It may be grooved and constructed as represented in Figure 3, so
that the atmospheric air alone shall enter and act upon the grooving.
Having tried by actual experiments all the above three ways, I have found that
the third is the best, and on it accordingly my Invention is partly based.
I may here observe that oblique plane surfaces, either on the exteriors or in the
interiors of projectiles, will tend to produce a rotary motion, as well as grooves or
channels.
Another error liäs been in the supposition that spiral passages in the interior of a
projectile would cause it to spin; but, in fact, the spinning agency, whether of the
exploding gas or of the atmospheric air, is exerted at the moment of their respective
entry and exit only, and no amount of spirality or helicality in the interior only of
a projectile can make it spin without obliquity of entry and of exit. And, more-
over, this obliquity, to produce the greatest effect, must be rectilinear, and not at all
spiral. On this principle my Invention is also partly founded.
My projectile then is so constructed that by the action of the atmospheric air
on certain rectilinear and oblique but not spiral passages, it is made to spin or
rotate on its longer axis, in its course through the air. For this purpose it is
essential that the explosive gas should be completely excluded from the said chan-
nels or grooves; and this is effected by a gas-clieck or valve-like contrivance. The
said channels or grooves may be on the external surface or in the interior, but my
experiments are in favor of the latter.
Having then in its interior and in its longer axis rectilinear and oblique channels
or grooves through which the atmospheric air may freely pass, my projectilo is
further provided at its posterior extremity, that is, next the gunpowder, with a
movable and detached valve or gas-check, by preference wholly or in part made of
india-rubber, so fitted that the force of the explosive gas pressing thereon completely
and hermetically blocks and prevents its own entry into the aforesaid grooves or
channel during the passage of the projectile through the barrel. Immediately how-
ever on the projectile quitting the barrel the valve is forced off by the opposing

page_text: atmospheric air, which air by its passage through the aforesaid grooves or channels
communicates to the projectile a rotary or spinning motion. I use no wad, as though
the elastic valve or gas-check occupies the usual position of a wad, it is not intended
to serve such purpose, but that of a valve only. A wad in addition may however
be used.
My Invention then may be summarised as an elongated projectile having in its
longer axis, but not parallel therewith, grooves or channels (one or more) which are
at the same time both rectilinear and oblique, which grooves or channels permit the
free passage of the atmospheric air, with the addition of a contrivance in the nature
of an elastic valve, which, contrariwise, prevents the passage through the said
grooves or channels of the gunpowder gas or other explosive agent.
Figure 4 represents in side view one of my improved projectiles; Figure 5 is a
view of the front end; and Figure 6 a view of the rear end.
a, a, a, are three rectilinear oblique passages in the interior of the projectile,
tapering from the front to the rear; b represents the elastic valve.
"
It will be observed that there is sufficient room in the centre of the projectile
between the passages a, a, a, for the insertion of a shell or other exploding agent, if
required. For very small bullets however, or in case this intervening space should
not be required, the internal grooves or channels may be approximated to any
degree, or even so as to become united and form one single central cavity or passage,
as represented in Figure 7.
Figure 8 shows a larger projectile, with 4 (or there may be more or fewer) oblique
tapering passages.
A truly elastic valve (or wad) employed at the rear of the projectile not only
answers the special purpose herein-before described, but also completely prevents.
windage" or the escape between the barrel and the projectile of any portion of
the explosive gas; a great saving of the explosive agent is also effected thereby.
My Invention is adapted for both cannon and small arms, breech-loaders, and
muzzle-loaders, and though specially intended for smooth or unrified barrels may
also be advantageously used for rifled barrels.
In witness whereof, I, the said Alexander Charles Mac Leod, have hereunto
set my hand and seal, this Sixth day of February, One thousand eight
hundred and seventy-nine.
A. C. MAC LEOD. (L.S.)