4 
is true universally ; there no modifying causes interfere to dunimsh 
the force, or limit the application of the great principle, and ^'e see 
strikingly that as facts accumulate, and facts are the capital of 
inductive science, fresh employment is everywhere provided for 
those who are willing to work. Take any one of the inductive 
sciences as an example, and we at once see how this is. Take for 
instance chemistry, compare it as it now is with what it w^ when 
Priestley commenced his career. The whole of the science then con- 
sisted of an imperfect knowledge of the properties of a few of the 
metals, of sulphur, phosphorus, and the three alkalies as they were 
then called. There was a little known also about salts and acids, and 
the existence of hydrogen and carbonic acid gas had recently been 
ascertained. In a range so limited there was httle room but for one 
master mind, when Priestley discovered oxygen, and at once an open- 
ing was made for researches into the nature of the atmosphere, of 
water, and of combustion, of the acids and the alkahes, and ample 
employment was provided for a host of distinguished philosophers 
for years to come. Other important discoveries were soon made, 
each becoming as it were a new origin of light, throwing perhaps 
at first but feeble rays upon the objects around us, but reve^ng so 
much of their strange forms as to excite curiosity, and awaken the 
strongest passion of the human mind,— the desire to discover the 
truth. Inorganic chemistry was then rapidly becommg a great 
science, when the foundations of organic chemistry were laid m a 
succession of brilliant discoveries. That was but a few years ago, 
but there were many men then ready trained for the work, and the 
progress was proportionally rapid. To take a few of the disco- 
veries in organic chemistry, and show how each has been the germ 
of others, as it were the first term of a diverging series, and thus 
to exhibit the great principle at work that in science labour creates 
a demand for labour, might perhaps be of some interest, but it would 
lead me from the object which I have in idew, which is simply to 
point out the grounds upon which I have ever felt a strong conviction, 
that whatever means were placed at the disposal of the Royal Society, 
no lasting difficulty could occur in turning them to useful account. 
Durin®- the last year considerable progress has been made by Mr. 
Hopkins'^in the important experiments which he has been carrying 
on in conjunction with Mr. Fairbairn and Mr. Joule. lou no 
doubt are aware, that, as we descend below the surface of the earth, 
it has been found that the temperature increases : numerous experi- 
ments made in different places with all the necessary precautions to 
guard against fallacy, seem clearly to have established the fact. The 
increase is about one degree of Fahrenheit for a depth of from 50 to 
60 feet. If. therefore the conducting power of the materials ot the 
o-lobe was the same at all depths, we should have a series, vhich 
would give us the depth proportional to every required temperature. 
Reasoning in this way, we conclude that a temperature higher than 
that of melting iron exists at a depth of thirty miles, and that at 
double that depth the materials of thesurface of the globe, combined as 
we find them in nature, would enter into fusion. It has therefore been 
