Mr. Rennie’s account of experiments , &c. 119 
and approximations. Professor Robison in his excellent 
treatise in the Encyclopedia Britannica ; Banks, on the power 
of machines ; Dr. Anderson of Glasgow ; Colonel Beaufoy, 
&c. are those, amongst our countrymen, who have given the 
result of their experiments on wood, and iron. The subject, 
however, appears to have excited considerable attention on 
the continent. A theory was published in the year 1638, by 
Galileo, on the resistance of solids, and subsequently, by 
many other philosophers. But however plausible these inves- 
tigations appeared, they were more theoretical than practical, 
as will be seen in the sequel. It is only by deriving a theory 
from careful and well directed experiments, that practical 
results can be obtained. It would be useless to enumerate 
the labours of those philosophers, who in following, or vary- 
ing from the steps of Galileo, have merely tended to obscure 
a subject respecting which they had no data to proceed upon. 
It is sufficient to enumerate the names of those who, in con- 
junction with our own countrymen, have added their labours 
to the little knowledge we possess. The experiments of 
Buffon, recorded in the Annals of the Academy of Sciences 
at Paris, in the years 1740 and 1741, were on a scale suffici- 
ently large to justify every conclusion, had he not omitted to 
ascertain the direct and absolute strength of the timber em- 
ployed. It however appeared from his experiments, that the 
strength of the ligneous fibre is nearly in proportion to the 
specific gravity. Muschenbroeck, whose accuracy (it is said) 
entitled him to confidence, made a number of experiments on 
wood and iron, which by being tried on various specimens 
of the same materials, afforded a mean result considerably 
higher than other previous authorities. Experiments have 
