Where did Life Begin? 19 



of the earth had reached the same tempera- 

 ture and cHmatic conditions. Well, time is 

 the Infinite factor in every calculation of this 

 sort; nature, reason, and observation unite 

 in saying " it is illimitable and all-sufhcient." 

 Certainly there has been and will be time 

 enough for everything. 



If the first isothermal belt, including the 

 highest heat degrees in which any life is pos- 

 sible had swept southward at the rate of one 

 English mile in a millennium, it would have 

 taken about 6,000,000 years for it to have 

 travelled from the north pole to the equator. 

 This would seem a sufficient lapse of time for 

 a great advance and development of all forms 

 of life moving within the zone. I am well 

 aware that eminent geologists are assuming 

 much longer periods for the life-history ; for 

 instance Professor Dana mentions 48,000,000 

 years as an estimated minimum of time since 

 the commencement of the Silurian age ; while 

 Sir William Thomson estimates ofeoloelcal 

 time at 100,000,000 years, Haughton at twice 

 that period, and many others at thousands 

 of millions. Now, without courtinor an ear- 



