IMPROVEMENTS IN CONSTRUCTING ROADS AND STREETS
Year: 1865

page_text: .
LETTERS PATENT to Joseph Mitchell, of Inverness, Scotland, Civil
Engineer, for the Invention of "IMPROVEMENTS IN CONSTRUCTING ROADS
AND STREETS."
Sealed the 31st October 1865, and dated the 5th May 1865.
PROVISIONAL SPECIFICATION left by the said Joseph Mitchell at the
Office of the Commissioners of Patents, with his Petition, on the
5th May 1865.
I, JOSEPH MITCHELL, of Inverness, Scotland, Civil Engineer, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN CONSTRUCTING
ROADS AND STREETS," to be as follows:-
In constructing roads and streets according to this Invention the whole
surface of the foundation of the road is to be brought to the inclination and
convexity fixed on, and then beat hard and smooth with beaters. On this
surface concrete metal is to be laid (thrown from a height of six to ten feet)
to a depth of twelve inches for a street, and to a less or greater depth according
to the peculiarity of the traffic. and beat hard with beaters: any apparent
interstices filled up with a grout of cement and sand, and the whole rolled over
with a roller of two tons weight.
The cross section of the road should have a convexity of eight inches for a
roadway of thirty feet in width, and so in proportion for a greater or less
width.

page_text: The materials for the concrete should be in the following proporti
such other as may meet the exigences of the street or road:-
Whinstone metal screened with a harp, and if necessary washed
with water so as effectually to remove all earth or clayey
particles
4 par
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Joseph Mitchell in the Great Seal Patent Office on the
1st November 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
MITCHELL, of Inverness, Scotland, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifth day of May, in the year of our Lord
One thousand eight hundred and sixty-five, in the twenty-eighth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Joseph Mitchell, Her special licence that I, the said Joseph Mitchell, my
executors, administrators, and assigns or such others as I, the said Joseph
Mitchell, my executors, administrators, and 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 ROADS AND STREETS," upon the condition (amongst others)
that I, the said Joseph Mitchell, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and seals,

page_text: 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 Joseph Mitchell, 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 thereof, that is to say:-
In constructing roads and streets according to this Invention, the whole
surface of the foundation of the road or street, whether for concrete or pave-
ment, is to be brought to the inclination and convexity fixed on, and then
watered and rolled with a heavy iron roller. On this surface concrete metal is
to be laid to a depth of eight inches for a street or road, or to a less or greater
depth, according to the locality and peculiarity of the traffic, and beat hard
with beaters; any apparent interstices on the surface are to be filled up with
a grout of cement and sand before consolidation, and the whole rolled over
if necessary with a heavy iron roller.
The cross section of the road or street should have a convexity of eight inches
for thirty feet in width, and in like proportion for a greater or less width.
The materials for the concrete should be in the following proportions, or
such other as may meet the exigences of the street or road:-
Broken stones such as are ordinarily used, of uniform size (no flat
stones) not exceeding 2 inches in their largest dimensions, and
if necessary washed with water so as effectually to remove all
earth or clayey particles
Clean sharp sand
-
4 parts.
1. part.
Roman or Portland Cement or cement of the character of
Roman or Portland employed, combined or separately, pro-
vided the quality is such as to set in a few hours
-
-
1 part.
In all 6 parts.
The whole to be thoroughly mixed with water, so that every part of the
broken materials shall be coated with the liquid cement, and laid in place on
the road, and then beat down to the required inclination and convexity of
the mattince takes place The surface to be left for some hours

page_text: tion, as above described, but on which generally a less. depth of the concrete
will be required, I in each case form a surface or bed of cement concrete of
like proportions, viz., 4 parts clean sharp gravel or broken stones, I part sand,
and 1 part cement above named, is to be laid 3 to four inches deep in a perfect
and regular section, on which paved causeway granite blocks are to be placed.
It is desirable that the surface thus formed of concrete and thoroughly beaten,
should be allowed to set; so as to become hard before placing the paving stones
thereon, but this is not essential; it is however important that in laying the
stones on a surface made of cement concrete according to my Invention, that
they should not be beaten as heretofore. These stones, by preference, should
be six inches in depth, three inches thick, and nine to twelve inches in length,
or such other dimensions as the exigences of the traffic may require, and when
the paving stones have been regularly and perfectly laid according to the cross-
section of the roadway, the joints are to be filled with cement grout, one part
sand and one cement; the whole to be left without traffic for 48 hours, or
until the cement is firmly and thoroughly set.
The peculiarity of this Invention consists in the employment of hydraulic
cement concrete as above specified, which is unaffected by the atmosphere,
either heat or rain, which is not the case with lime, asphalte, or other mixtures
that have hitherto been used for streets or roads.
In witness whereof, I, the said Joseph Mitchell, have hereunto set my
hand and seal, this Twenty-fifth day of October, in the year of our Lord
One thousand eight hundred and sixty-five.
TAG
JOS. MITCHELL
L.S.)