168 
On the Mines of Mexico. ' 
to the strength of materials. They confirm tlie law of Galileo, 
that the transverse strength depends as well on the length and 
depth of the bar, as on its section of fracture being diminished 
in the simple proportion of the length, and increased in the 
simple proportion of the depth. They also shew, that the de- 
flection of beams is exactly proportional to the pressure which 
they sustain ; at least until they become overloaded, when the 
deflection becomes irregular, in consequence of the beam begin- 
ning to give way. Lastly, they shew, that, in the case of Me- 
mel fir, it is always unsafe to load the beam with any more than 
one-half of what will break it. 
The following is another series of experiments made in the. 
succeeding year. 
( To he continued. ) 
Art. XXI I . — On the Mines cf Mexico. Communicated by a 
Gentleman intimately connected with Mexico. 
I HE public attention has of late been directed in an unusual 
degree to the former possessions of Spain in the western world. 
It is now fully three centuries since both Mexico and Peru be- 
came known by report to Europeans, and it is natural for the 
public to inquire the causes of so long a period having elapsed, 
without a more direct acquaintance with these deposits of mine- 
ral treasure. The Government of Old Spain,^ bigotted equally 
in commerce and religion, forbade all intercourse between her 
colonies and the rest of Europe ; and it happened, unfortunate- 
ly, that England and Holland, the States best fitted to turn the 
wealth of these colonies to account, were long debarred from a 
connection with them, by a succession of untoward circumstances. 
If we go back to the seventeenth century, the era of the naval 
greatness of the Dutch, we find that their hostilities towards the 
subjects of the Spanish crown were confined in general to the 
East Indies. The naval power of England became conspicuous 
soon after, but, during the reign of the dreaded Louis XIV., it 
was directed wholly against France ; and it was not until the 
war that began in 1740, that our countrymen made an attempt 
to wrest from Spain the fairest portion of her transatlantic pos- 
L 2 
