IMPROVEMENTS IN CONSTRUCTING ASPHALTED ROADS, AND IN APPARATUS EMPLOYED THEREIN
Year: 1872

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn
Fields, in the County of Middlesex, Gentleman, for the Invention
of "IMPROVEMENTS IN CONSTRUCTING ASPHALTED ROADS, AND IN APPARATUS
EMPLOYED THEREIN."—A communication from abroad by Theodore
Robin and Anne Antoine Léon Malo, both of Paris, in the Republic
of France.
Sealed the 13th August 1872, and dated the 26th February 1872.
PROVISIONAL SPECIFICATION left by the said John Henry Jolinson
at the Office of the Commissioners of Patents, with his Petition, .
on the 26th February 1872.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County
of Middlesex, Gentleman, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN CONSTRUCTING ASPHALTED ROADS, AND IN
APPARATUS EMPLOYED THEREIN," a communication from abroad by Theodore
Robin and Anne Antoine Lèon Malo, both of Paris, in the Republic of
France, to be as follows:-
"
The methods hitherto employed in constructing asphalted roads are
defective for various reasons, which are chiefly the following, viz., first,
the difficulty in heating the powder to exactly the requisite temperature
in order not to allow the bitumen with which it is impregnated to

page_text: pleted the roller bears on the asphalte only without touching the
rails.
When it is desired to operate on the adjoining strip one of the rails is
replaced by a strip of flat iron which is laid on the bed of asphalte which
has been already compressed, so as to compensate for the difference of
depth between it and the other rail, and the operation is then proceeded
with in the manner herein-before described. The strip which extends
along the length of the kirb stone, and the width of which does not
exceed that of the foot of the rail, may be readily compressed, either by
means of a rammer or with the roller itself, which would then act on a
false bearing. The same process may be employed for any depth.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson in the Great Seal Patent
Office on the 20th August 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-sixth day of February, in the
year of our Lord One thousand eight hundred and seventy-two, in the
thirty-fifth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said John Henry Johnson,
Her special license that I, the said John Henry Johnson, my
executors, administrators, and assigns, or such others as I, the said
John Henry Johnson, my executors, administrators, or assigns, should
at any time agree with, and no others, from time to time and at
all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and
Isle of Man, an Invention for "IMPROVEMENTS IN CONSTRUCTING ASPHALTED
ROADS, AND IN APPARATUS EMPLOYED THEREIN," & communication to me from
abroad by Theodore Robin and Anne Antoine Léon Malo, both of
Paris, in the Republic of France, upon the condition (amongst others)
that I, the said John Henry Johnson, my executors or administrators, by

page_text: an instrument in writing under my hand and seal, should particularly
describe and ascertain the nature of the said Invention, and in what
manner the same was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Henry Johnson, do hereby
declare the nature of the said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the accom-
panying Drawings, and to the letters and figures marked thereon,
that is to say :-
The methods hitherto employed in constructing compressed asphalted
roads are defective for various reasons, which are chiefly the following,
namely, 1st, the difficulty in heating the powder to exactly the requisite
temperature in order not to allow the bitumen with which it is impreg-
nated to evaporate, and, 2nd, when the heated powder has been spread
over the ground, the difficulty in compressing it uniformly and with suf-
ficient power to enable it to withstand the immediate traffic of vehicles.
Rammers and rollers as hitherto employed are very defective tools for
the purpose, the former because whilst compressing the portion on which
they fall they disturb and unsettle the adjoining parts, and the latter
because they cannot exceed a certain weight without crushing and
driving the powder in front of them before they have had time to
compress it, which defects it is the object of this Invention to remedy.
According to this Invention it is proposed to employ rock asphalte,
either pulverized or simply crushed, and either natural as found in
mines, or factitious, that is to say, white stone artificially impregnated
with bitumen. This rock may be employed either in a heated state or
cold, the latter alternative constituting one of the most novel points in
this Invention.
The rock is compressed by means of a steam roller of sufficient weight
to effect a compressing force of from 9 to 12 cwt. per square inch. This
roller is so operated that the compression shall take place methodically
and progressively without the asphalte being crushed or driven before
the roller, as is the case when compressing asphalte powder in the
ordinary manner with very heavy rollers.

page_text: The operation is carried out in the following manner:-Suppose it be
desired to asphalte a street for the whole or a portion of its length, two
rows or lines of rails A, B, of the form and proportions or their equivalent
shown in the annexed Drawing are laid down longitudinally, about a
yard apart, the inner faces of such rails being smooth and vertical.
Between these two rails there is laid a bed of crushed or pulverized
asphalte C, of a depth of about three inches, or say about the depth of the
rails. A roller D is then passed over the rails, and a projection d, d,
which is formed on the central portion of the roller of a width corre-
sponding to the width between the rails compresses the asphalte to the
extent of the whole depth of this projection, say for example about ths
of an inch. When this roller has arrived at the end of its course the
rails are replaced by others about ths of an inch less in height, and
the roller is passed over the asphalte again, thus compressing the bed of
asphalte to the extent of ths of an inch more, and so on in succession
until the compression being completed the roller bears on the asphalte
only without touching the rails.
When it is desired to operate on the adjoining strip one of the rails A
is replaced by a strip of flat iron, which is laid on the bed of asphalte
which has been already compressed, so as to compensate for the difference
of depth between it and the rail B, and the operation is then proceeded
with in the manner herein-before described. The strip of asphalte which
extends along the length of the kirb stone, and the width of which does
not exceed that of the foot of the rail, may be readily compressed, either
by means of a rammer or with the roller itself, which would then act as
a false bearing. The same process may be employed for any depth.
The Figures 1 to 5 of the Drawings represent the gradual compression
of the asphalte from its first laying in Figure 1 to its thorough com-
pression in Figure 5.
In witness whereof, I, the said John Henry Johnson, have to
this my Specification set my hand and seal, this Thirtieth day
J. HENRY JOHNSON. (L.S.)