470 MEMORIAM : WILLIAM ACKROYD, F.I.C., F.C.S. 
above Malham, the patient watching at the springs, and the 
solemnities connected with the estabhshment of the central 
testing station at the Buck Hotel, where Mr. Ackroyd presided 
with impressive dignity over the array of pipettes and reagents 
by which the shoals of bottles from the springs were tested. And 
as the shades of evening lengthened the lengthening faces of the 
disappointed chemists, as no results appeared, will never be 
forgotten by the writer. Ackroyd was one of those who, through 
the tantalising twelve days before the tests came out, manfully 
struggled with hampers of bottles duly forwarded from Malham — 
and no one was gayer than he when the results which he embodied 
in his chlorine-curve diagram were slowly revealed. His un- 
flagging industry was also manifested in the early Ingleborough 
investigations, when 1,200 tests were examined, most of them, 
I believe, by Mr. Ackroyd himself. 
One of his colleagues in this investigation gives the following- 
impression of Mr. Ackroyd's personality and work : — "Ackroyd 
was, in some respects, an ideal colleague to work with, as he 
never spared himself, and if an idea had to be worked out, his 
example, as evidenced by unremitting attention to the problem 
in hand, stimulated all those who worked with him to their 
best effort. His chemical work was always painstaking and 
accurate, and was accepted as such by his co-workers. Those 
who knew him intimately were aware that some of his theoretical 
deductions in phj^sics did not command general assent, but even 
in this domain his experimental work was original, ingenious, 
and resourceful. As a colleague he was very accessible, and as 
one who worked very closely with him whilst the Malham re- 
searches were being conducted, I can say how exceedingly 
valuable his help was to the Society. Without such helpers 
conjoint work such as was successfully carried out at Malham 
and elsewhere would have been either delayed indefinitely or 
prevented altogether." 
Professor Joly's attempt to calculate the age of the earth 
by a comparison of the salt carried dovm. each year by rivers 
and that contained in the ocean, found a searching critic and 
vigorous opponent in Mr. Ackroyd. His attention had been 
drawn to the clilorine constituent in river water during the 
