16 REPORT—1848. 
I beg leave to submit this subject to the Association as one worthy of notice, 
observing that in this case, as in all others where water acts by its gravity or 
pressure, those machines do the best duty where the water enters the machine 
without shock or impulse and quits it without velocity. We then obtain all 
the available power that the water will yield, with the least loss of effect, 
and this result is best accomplished by making the pipes and passages of 
sufficient and ample size to prevent acceleration of the hydrostatic column. 
Description of the Figures. 
The three figures given in Plate I. show an elevation, plan and section of _ 
the water-pressure engine at the Alport Mines. The arrows show the ; 
entrance and escape of the water which works the engine. The influx and 
efflux are regulated by two sluices, which are raised by screws, and determine 
the speed of the engine and of the up and down strokes of the piston. 
Eo eS 
On the Air and Water of Towns. ; 
By Rosert Anevus Smitu, PA.D., Manchester. f 
Havine been requested to examine into the variations in composition of the 
air and water of towns, I send the observations which I have made upon the — 
subject. ; 
It has been long believed that the air and the water have a most import- 
ant influence on our health, and superstitions have therefore constantly been 
attaching themselves to receptacles of the one and emanations of the other. 
The town has always been found to differ from the country ; this general 
feeling is a more decisive experiment than any that can be made in a labo- 
ratory. Although men of high standing have been found to deny that any 
difference exists between the air of the worst towns or the most crowded 
rooms and that of the open country, it seems to be only a proof, that men 
accustomed to experimental inquiry are apt to forget the value and force to 
be attached to those apparently less rigorous observations which the senses 
are constantly and unconsciously making, and to believe only that which can 
be demonstrated by the grosser processes of a laboratory. Most men would 
be satisfied of the impurity of an atmosphere through which a blue sky could 
never be seen of a blue colour, or where a bright cloud appears of a dingy 
brown ; but there are men who take this air into glass receivers, and because 
they detect no new substances or strange compounds, they deny that there is 
any peculiarity. I have known persons from the highlands of Scotland who 
felt in going into Glasgow as we do when going into a glass-house or forge, 
and who could not be persuaded to stay, unless they remained long enough 
to find some advantages before unknown to them. The inquiries made by 
the Sanitary Commissioners have completely established the fact that crowded — 
towns are dangerous places; and although it is still an open question whe- 
ther a well-regulated town or country life be the more healthy, it is suffi- 
ciently established that our towns have subjected themselves to many dangers, _ 
which we in self-defence are feeling compelled to try to avert, by acting ac- — 
cording to natural Jaws as far as their acquaintance has been made. 
Most persons must have felt that a rapid entrance into a large town, — 
especially a manufacturing town, was also an entrance into another climate. — 
An inhabitant of the sea-coast or of the hills perceives it rapidly, and the 
effect on them is often decidedly bad; to those accustomed to it a few 
hours are found to be enough to cause them to forget the atmosphere which — 
in their holiday excursions had caused them such delight. We are apt in 
