The Washington union., 1857-08-19

this size which would give the engineer an ultimate
pressure upon his brakes Of ten thousand pounds
The two systems may be readily compared Or,
rather they NAV be contrasted In the example have
taken of approaching collision the Washington and
Baltimore road the engineer supposed to sec the danger
a half mile OH. He commands the retardmg power by
signal to two brakesmen. These men, WITH every df
gence can only place brake pressure OF twelve hundred
hounds on two cars of the train in fifteen seconds They
then double this pressure in fifteen seconds more Their
ultimate retaTding force Is thus 400 pounds exered
the thirty wheels OF four cars Inc pressure on each
Of these thirtytwo wheels there being eight wheels o
carl can only amount seyenty-fve pounds, and this
tension is attained after lapse Of thirty seconds
let ms now see in what time and with what force the
same engineer brake tram by means Oh ts mcDon
aid invention :.
In the case supposed life is TO be saved If saved at ALL
in one minute Of time. Whatever of retarding force
NAV be commanded must be promptly applied by this
Mcdonald brake the agency of these cheap bakesmenb
dispensed with The engineer is made self-reant his
bakesnen are iron brakesmen his messenger TO do his
bidding issues from the stean-chest and Is instant and
potential in its action The danger is perceived, and by
motion of his hand, in moments time rearding
pressure Of se thousand pounds double that amount
If the extra cylinder be enlarged, may be brought TO
bear upon all the wheels OF each car OF his train
The comparative efficiency of the two systems may 10
stated In figures Under the present system an aggregate
pressure Of 400 pounds be applied to the train IN
thirty seconds of time This is brake pressure of
enty-fvc pounds ON each Of thirty-two wheels
Under the Mcdonald system an aggregate pressure
of time This pressure is brought not on the wheels
four cars as under the present system but on oil the
wheels of the Fix which compose the train This
equivalent to hundred pounds each OF fortyegh
wheels.
The comparison OF contrast is briefly thus total
tarpg force on the train of 400 pounds against to,
tai of 10 900 pounds by the Mcdonald system power
in detail of seventy-fve pounds each OF thirtywo
wheels against power in detail of two hundred pounds
on each OF fory-eght wheels by the Mcdonald system
In point of time the comparison is as one second to
thirty seconds.
These disparities between the systems in time and
in power constitute the difference between efficiency and
;ueccy or to sum it up in ewest words it is the diff
ference between life and death in nine out of ten
/ sudden emergency.
Enough has been said to rivet attention. have at
tempted no description of this invention have only
given its valuable attributes in contrast with the very
meagre energies of the present system. That my state
ments are true avouch the fact itself The Mcdonald
brake at work of the express trains of the Rich
mond and Fredericksburg railroad 1t has been in use
there for five months and may be examined at any time
That it possesses this prompttude and power for ec
gences avouch the president and officers OF the road
that it does its work with facility and absolute precision
avouch the engineer who rests in the security OF its IN
slant power
with all this to commend its adoption this Mcdonald
brake is new thing and has TO struggle into against
an established system The present system imbecie and
murderous it is admitted to be- is difficult OF over
throw 1t occupies the field and opposes to all reform
| els inertia that defies an innovation
hope through your columns to shake this vicious sys
tenn with all its nonsrous defects, and to substitute
system of brake perfectly simple in its device, and inn.
| ntely more efficient in its operation. A. J. M
WARRESToN, FAUouIER, VIRGINIA.