Patents^ 
437 
tion at the time of taking out the patent or filing the specification, 
I strongly incline to think, this ought to be the case, either at th6 
filing of the specification or within some reasonable time after, ac- 
cording to the nature of the invention : but I do not find it laid 
down as necessary. How can it be ascertained that an invention 
is useful, and deserving of a patent right, till it be shewn to be soj 
by actual experiment ? or why should a patentee enjoy his right 
to a monopoly, who leaves other persons at their own risk to as- 
certain the practicability and utility of the proposed invention ? 
1 Ithly. Moreover, I think it may be inferred from the observa- 
tions of some of the bench arguendo, that the person who merely 
suggests a theory or principle^ is not entitled to a patent, but he 
only is so entitled, who first reduces it to practice and ascertains 
at his own expence of time, money and labour, the utility of the 
proposal. And this appears to me so reasonable, that I think it 
may well be adopted under some limitations. Sufficient time 
should be allowed to the first person who suggests an usefui prin-t 
ciple to reduce it to practice : a time, that must be limited ac- 
cording to the nature of the invention. A man can easily put to- 
gether his improvements on the escapement of a watch, for in- 
stance ; but a steam engine is not perfected in a week, or a month, 
or a twelve-month. If a man will permit his suggestions to lay- 
idle and fruitless for years, he ought to be considered as having 
abandoned any exclusive right to them. Indeed all the common 
doctrine of abandonment, will apply to patents. 
It is upon this principle, that the patent to Livingston and 
Fulton for their steam boats can be best defended. Fitch lost his 
right by abandonment through non-user. Rumsey did not suc- 
ceed so as to bring his steam boat into full use. Lord Stanhope 
also failed in England. After these failures, the persons who suc- 
ceeded, appear to have a reasonable claim to a patent monopoly, 
sufficiently extensive to cover the whole application of steam to 
the impelling of vessels on water ; for less would hardly justify 
so expensive an experiment. 
12thly. A patent may be set aside by scire facias, or stopt ia 
limine by caveat ; but as in England every person takes out a pa- 
tent at his own risk, and on his own responsibility, the usual course 
is, that persons willing to contest the patent right, use the inven- 
tion and leave the patentee to his remedy at law. This remedy 
is an action on the case against the person infringing the patent 
right. The declaration should set forth the invention in general 
terms, the patent, the specification duly enrolled, with averments 
VoL II 3 K 
