145 
and the instruments employed in these experiments were exhi- 
bited in action before the Academy. | 
The author made some remarks as to the unexpected slow- 
ness of transit of these pulses, and ascribed deficiency of velocity 
as predictable from the theory of elastic moduli, as probably 
due to the imperfect homogeneity and continuity of the media 
operated on. The relation that his results bore to those re- 
cently obtained as to the rate of sound in wrought iron, as de- 
termined in France, suggested that the hitherto received theory 
of sounds in solids would probably require to undergo revision. 
Sir William Betham read a paper on the account of Thomas 
de Chaddisworth, Custodee of the Temporalities of the Arch- 
bishop of Dublin, from 1221 to 1256, from the Great Roll of 
the Pipe. 
*‘ The Academy require no evidence to satisfy them, that 
in historic importance the records of the country are the surest 
and safest guides to the historian. No histories of Ireland, yet 
published, synchronize with the records, but for the most part 
are delusive and erroneous. 
“© Nearly half of the last decade of the first moiety of a 
century has passed since I commenced an investigation into 
the ancient records of Ireland; and my accumulation of volumes 
of manuscripts on the subject surprise even myself. Much was 
done by the Record Commission, appointed in 1810, and the 
ponderous volumes published by it demonstrate the value of the 
muniments of the country, although they have not accom- 
plished an object at all commensurate with the expenditure. 
“‘ Little was done by that Commission to preserve them, or 
make the records available. The subject has been brought 
under the consideration of the Government of many adminis- 
trations ; about four years since commissioners were appointed 
_ to investigate the present state of the Irish records; their 
report has been made, and a bill was prepared to provide for 
their safe custody, which has been long in the hands of the 
VOL. V. L 
