On the Water of Tunbridge Wells. 353 
analyzed at my request by Dr. Lambe and Mr. Brande, and 
the lead detected; and I believe some other gentlemen, of 
known chemical abilities, also procured lead from the water, 
the greater part of which was in a state of suspension. It is 
an incidental confirmation of the fact, that the lady alluded to 
above was a water drinker, and partook largely of it. A seri- 
ous alarm was, therefore, reasonably created at the time, but 
Mr. Taylor has substituted cast-iron pipes, and no complaint 
similar to the one which was so troublesome in 1815 has since 
made its appearance. I entertained an opinion, however, when 
the evil prevailed, that it might in time cure itself, for deposi- 
tions from the water would probably coat the internal surface 
of the pipes, and defend it from the action of the water; some 
other circumstances also induced me to form this opinion, but 
the mischief which was in the mean time done to individuals, 
would not admit of delay, and I pressed upon Mr. Taylor the 
propriety of taking away the leaden pipes. The water at the 
fountain-head is perfectly good and pure, for that has been also 
analyzed. Thus the minds of the residenters and visitors, 
who may live in those houses to which this water is distributed, 
may be quieted, but still it would be prudent, on all accounts, 
to filter the water used for drinking. 
Iam, dear Sir, 
Yours faithfully, 
17, Queen-street, May-Fair, G. D. Yeats. 
Dec. 11, 1822. 
Art. XII. An Investigation of the Methods used for ap- 
proximating to the Roots of Affected Equations. By 
Davies Gilbert, F.R.S., F.A.S., &c.; in a Letter to the 
Editor of the Quarterly Journal. 
Dear Sir, 
Ir is well known that several mathematicians have recently 
extended to Affected Equations, the method long in use for 
approximating to the root in cases where one power alone ap- 
pears; each following a different line of induction, and originat- 
ing his system independently of the others. The subject has 
Vou, XIV. 2A 
