60 ANNIVEKSAKY ADDllESS 



only a severe winter, as we do, in a cycle of years. I only wish 

 to indicate the principle. It would be very interesting for 

 geologists to study our sun's climate, as revealed in the geological 

 records of the earth, and not only his winters, but also his summers 

 — his hot periods. I do not pretend to be a geologist, but when I 

 see a coal fire I cannot help speculating on the number of sun's 

 summers that coal has experienced to be changed from a mass of 

 vegetable fibre to a mass almost mineral in structure ._ I can 

 imagine one summer of the sun drying up the moisture from the 

 peaty mass, and others distilling and condensing in nature's 

 retort those oils which our enterprising American cousins tap 

 with such profit. The evidence of hot seasons is perhaps less 

 marked than the evidence of cold seasons, because no boulders are 

 brought from a distance and left as evidence. Yet I think that 

 the sun's hot periods may have still left geological evidence of 

 their existence which may be well worthy of investigation. Last 

 year Mr. John Evans took us to see the Rough Down chalk-pit at 

 Boxmoor, and he very particularly pointed out to us some veins of 

 what is called the Chalk Eoek ; it was strong and much harder and 

 denser than the other chalk, and I can easily imagine that great 

 heat might convert it into marble. We may therefore not only 

 study the age of the earth from its sun's winter, but also from its 

 summer. If the science of Palaeontology were more perfect, it 

 would doubtless afford evidence of an alternate series of hot and 

 cold periods on the earth in the same place, and I think the kind of 

 animals would be found to correspond with the climate of the sun 

 and therefore of the earth. 



When I spoke of the age of the earth, I should have been more 

 correct if I had said the age of the crust of the earth, for the age 

 of the earth and the age of the crust of the earth are quite diiferent. 

 Tlie age of the crust of the earth, great as it is, must be con- 

 sidered as ephemeral compared with the age of the earth itself. 

 Eor instance, if I say I am 50 years old, I do not mean to say that 

 the atoms of which my body is composed are only 50 years old, or 

 that if an oak is 500 years old, the carbon of which it is in a 

 great measure composed is only 500 years old. The matter in my 

 body may be eternal — at least, it has doubtless animated thousands 

 of animals and plants before I became seized of it for my temporary 

 use, and doubtless when I have done with it other animals and 

 plants will be animated by it. I may illustrate this by mentioning 

 what is taking place at the present moment in Watford and the 

 Atlantic. Huxley says, "I have ventured to speak of the Atlantic 

 mud as modern chalk." Investigations have demonstrated the 



