Page:Petition and Case of Joseph Bramah.pdf/3

 them for the ſame Purpoſe to the next Generation. But beſide theſe, there is yet another Objection of ſtill greater Conſequence, and againſt which this Principle cannot poſſibly provide a Remedy. Though the Diſpoſition of the Wards be ever ſo artful, novel, and judicious, a ſkilful Workman, having Acceſs to the Entrance, will be at no Loſs to fabricate a Key, which ſhall tally as perfectly with them as if the Lock had been open to his Inſpection; and this Operation may not only be performed to the higheſt Degree of Certainty and Exactneſs, but is conducted likewiſe with the utmoſt Eaſe, and without any extraordinary Genius or mechanical Skill; for the Bit, which is intended to receive the Impreſſion, being fitted to the Key-hole, and the Shank of the Key bored to a ſufficient Depth to admit the Pipe, nothing remains but to colour the Bit with a Preparation, which, by a gentle Preſſure againſt the introductory Ward, may receive its Impreſſion, and thus furniſh a certain Direction for the Application of the Tool. The Bit being made to tally with the Firſt Ward, gains Admiſſion to the Second; and a Repetition of the ſame Means finally opens a Paſſage to the Bolt. It is from hence evident, that endleſs Variations in the Diſpoſition of fixed Wards are not alone ſufficient to the Purpoſe of perfect Security; and ſince no common Lock can be purchaſed, of which there is not an infinite Number of Duplicates abroad, all tending to induce a falſe Confidence, it might be queſtioned (was there no Remedy) whether the Vigilance and Caution every Man would have over his Property, in caſe no Locks were uſed, would not be a preferable Security.

The Evils which ſprang from theſe Defects had been long a Matter of ſerious Contemplation with me, when, after much intenſe Study, and many expenſive Experiments, I fortunately diſcovered a Faſtening to which none of the above mentioned Objections can poſſibly apply; and which I feel the utmoſt Aſſurance is abſolutely inviolable, and capable of Extenſion beyond all the Fineſſe of the ill-diſpoſed to overcome, by Force alone excepted. Its Properties and Mechaniſm are minutely explained in a Diſſertation on the Conſtruction of Locks publiſhed by myſelf, and they are conciſely as follows:

1ft. The Uſe of the Pick-lock is totally and effectually excluded.

2nd. No Inſtrument ſhort of the perfect Key, or an exact Duplicate thereof, can have the Capacity of opening the Lock.

3d. There is no Poſſibility of obtaining the Form of the proper Key from without by Impreſſion, having Acceſs to the Key-hole.

4th. The Lock in Principle is capable of infinite Variation, without Difference of Magnitude or Shape; ſo that Locks may be fabricated with component Parts of preciſely the ſame Dimenſions, to the moſt remote Period of Futurity, without One Duplicate or Counter Part of any former, and re-arranged for One Key to paſs the Whole. Conſequently the Poſſeſſor of a Lock may make a Variation whenever Occaſion requires, which ſhall exclude any former Key.

This Property of Tranſpoſition, which ſuperſedes all Apprehenſions from falſe Keys, is clearly evinced by the following Arithmetical Table, which ſhews the proportional and the actual Sum of Security contained in each Lock, conſiſting of any given Number of Guards from Unity to Twenty-five; viz. ſo much of their Security only as reſults from the different Arrangements of their component Parts.