Professor Nicholson's second law is, however, more speculative and less reliable in its action. It seems to imply some absolute limit to the number of great inventions. Radical changes are no doubt generally followed by smaller increments of invention; but we can have no guarantee that new radical changes quite as important as the earlier ones may not occur in the future. There are no assignable limits to the progress of mechanical invention, or to the rate at which that progress may be effected. If certain preliminary difficulties in the general application of electricity as a motor can be overcome, there is every reason to believe that, with the improved means of rapidly communicating knowledge we possess, our factory system may be reorganised and labour displaced far more rapidly than in the case of steam, and at a rate which might greatly exceed the capacity of labour to adjust itself to the new industrial conditions. At any rate we are not at liberty to take for granted that the mobility of labour must always keep pace with the application of new and labour-disturbing inventions. Since we are not able to assume that the market will be extended _pari passu_ with the betterment in methods of production, it is evident that improvements in machinery must be reckoned as a normal cause of insecurity of employment. The loss of employment may be only "temporary," but as the life of a working man is also temporary, such loss may as a disturbing factor in the working life have a considerable importance.