272

EFFECT OF TAXES

the discovery of them, and in the last act of par-liament, reducing the assessed taxes, they ceased tobe chargeable.

From the changes thus suecessively introduced inthe number, the forms, and the positions of thewindows, a tolerable guess might, in some instances,be formed of the age of a house.

(305.) The effects of regulations of excise uponour home manufactures are often productive of in-convenience ; and check, in some measure, the naturalprogress of improvement. It is frequently necessary,for the purposes of revenue, to oblige manufacturersto take out a license, and to compel them to work ac-cording to certain rules, and to make stated quantitiesat each operation. When these quantities are large,as they usually are, they deter manufacturers frommaking experiments upon new' materials : they like-wise prevent them from discovering by trial, improvedmethods of conducting their processes. Difficultiesof this nature have occurred in experimenting uponglass for optical purposes; and in this case, per-mission has been obtained by fit persons to makethe experiments, without the interference of theexcise. It ought, however, to be remembered, thatsuch permission, if frequently granted, might beabused; and that the greatest protection againstsuch an abuse will be found, in bringing the force ofpublic opinion to bear upon scientific men,—and thusenabling the proper authorities, although themselvesbut moderately conversant with science, to judge ofthe propriety of the permission, by the public cha-racter of the applicant.

(306.) From the evidence given, in 1808, before