erected on the Mhie of Muran in Mexico. 243 



able. These parts cannot be shown in a drawing on a small 

 scale. 



The arrangements which are more especially novel in this 

 engine are, the mode of combining the effect of the cylinders, 

 and the carrying the piston rods through both ends of the 

 cylinders. 



The horizontal position affords a facility of concentrating 

 the power derived from even 4 or 6 cylinders upon one point, 

 and the carrying the piston rods through both ends of the 

 cylinders has the effect of preventing the weight of the piston 

 from producing unequal friction, owing to the state of tension 

 in which the rods are constantly kept. 



It is obvious that with an engine thus constructed, the 

 power may be divided and applied at each end ; or it may be 

 directed wholly to one end, by attaching at the opposite ex- 

 tremity a balance bob, or beam with a weight equal to half 

 the power of the engine. 



A common pumping engine with a beam requires that the 

 engine-house should be built close to the mouth of the shaft 

 in which the pumps are placed, which is often attended with 

 much inconvenience. The engine above described may be 

 merely covered by a shed, and this placed at any convenient 

 distance from the shaft. As mining engines are often re- 

 moved from one situation to another, the greater the facility 

 of fixing them, and the less masonry required, the more will 

 time and expense be saved. 



The engine which I have described, with three others built 

 in Cornwall under the superintendence of Mr. Woolf, and a 

 complete out-fit of founders', engineers', and millwrights' tools, 

 implements, &c., also saw-mills and stamping-mills, were 

 shipped on board the Melpomene, at Falmouth, on the 30th 

 of March 1 825, and arrived off the coast of Mexico the 27th 

 of May following. 



The Castle of St. Juan de Ulloa, which commands the 

 harbour of Vera Cruz, being at that time in the possession of 

 the Spaniards, the cargo was obliged to be landed on the 

 beacli at Mocambo, a league to the southward, which could 

 not be accomplished until the 10th of June, when the setting 

 in of the rains, and of the unhealthy season on the coast, oc- 

 casioned great suffering and the death of some of the trans- 

 port party. These circumstances prevented the machinery 

 being carried further than Santa Fe, which is about four 

 miles from the coast. 



Here Lieut. Cokjuhoun of the Royal Artillery, who had 



taken the charge of this most arduous enterprise, remained to 



recruit tlic health anil strength of the party under liis com- 



2 I 2 mand, 



