STATE GEOLOGIST. 19 
MODERN CEMENTS. 
Cements, as we know them today—meaning either natural or Portland 
cements—were not known commercially until the beginning of the last 
century. Indeed, Portland cement has not been manufactured on a com- 
mercial scale much longer than 50 years. The Roman cement was a 
natural cement, even more natural than cement bearing that name today— 
because it needed no burning, but was manufactured directly from the 
volcanic ashes around Mount Vesuvius, especially those found near Poz- 
zuoli, and it was therefore called Pozzuolana. 
Cements in England.—The first cements manufactured in modern 
times were made in England and were called “Roman Cements” from 
their resemblance to the old Roman cements which hardened under water. 
In 1756 while preparing to build the Eddystone light-house, John Smeaton 
began investigations which led to the discovery that argillaceous lime- 
stones produced limes that would set under water, called hydraulic limes. 
He carried his investigation far enough to secure a good hydraulic lime 
or natural cement, which through its durability in the Eddystone light- 
house gave Smeaton lasting fame in engineering science. The Eddy- 
stone light-house built in 1756-58 by Smeaton was on a very exposed 
coast in the English Channel south of Plymouth. It was rebuilt in 1882, 
not because of the failure of Smeaton’s cement, but due to the wearing 
away of the solid rock beneath the tower. 
In 1796, Joseph Parker, manufactured a Roman cement by calcining 
and crushing septaria nodules found on the Isle of Sheppey just off the 
coast of Kent, England. Parker’s patent, dated June 28, 1796, and num- 
bered 2120, claims the invention of: “A certain,Cement of Terras (trass) 
to be Used in Aquatic and other Buildings, and Stucco Work.” 
He described his process as follows: 
“The principle and nature of said invention consists in re- 
ducing tc powder certain stones or argillaceous productions, 
called noddles of clay, and using that powder with water so as 
to form a water (mortar?) or cement stronger and harder than 
any mortar or cement now prepared by artifical means. I do 
not know of any precise general term for these Noddles (?) of 
clay; but I mean by them certain stones of clay or concretions 
of clay, containing veins of calcareous matter, having fre- 
quently but not always water in the center, the cavity of which 
is covered with small crystals of the above calcareous matter 
—being burned with heat stronger than that used for burning 
lime—and by having water thrown upon them, and being re- 
duced to powder after burning, and being mixed with water 
just sufficient to make them into paste, become indurated in 
water in the space of an hour, or thereabouts. Any argilla- 
ceous stone, then, corresponding with this description, whether 
known by the name noddles of clay, or any other name, is the 
sort and kind only that I mean to appropriate to my own use 
in the fermentation (formation?) of my cement.” 
