558 INQUIRY INTO THE STRENGTH 
In estimating the value of any particular iron, 
it must be remembered, that its resistance, or 
rigidity under strain, is exclusively the criterion 
of its strength, but not the measure of its utility. 
Some irons of the very first quality exhibit weak- 
ness under strain, but possess, at the same time, 
great richness and fluidity, accompanied with 
elastic powers of no ordinary description. For 
example, the Ystalyfera No. 1, first sample, is an 
iron of this character, and although inferior to 
other irons, as respects strength, it has, neverthe- 
less, great flexure, the ultimate deflection being 
2.252, which is greater than that of any other iron 
I have yet experimented upon. In its powers to 
resist impact, it approaches nearly to the Gart- 
sherrie, Ponkey, and Elsicar irons, the numbers 
being— 
Garigherrie-ccrcccdtesecedavevers No. 3=998 
Ponkey clan eGiticion eitiajeie eles wislu(s'eie No. 3=992 Powers to resist 
BISiGAY seeecriaate ss cc Peakedeneeees No. 2—992 impact. 
Votalyfera wcicccactassvescesess No. 1=973 
No. 1 of the Ystalyfera second sample, is 
inferior, both as regards strength, and its powers 
of resisting impact. 
On comparing the results in the last table 
with those in the List of the General Summary, 
