68 ANNUAL OF SCIENTIFIC DISCOVERY. 



20,000 individuals. In England, almost every article of tin ware is 

 formed from these plates. Nearly two-thirds of the total manufacture 

 are exported, principally from Liverpool to the United States, where 

 they are also used considerably instead of slates for the roofs of build- 

 ings. The trade has been rapidly increasing. The exports of tin 

 plates were for the years ending the 5th January, 1847, declared 

 value, 639,223; 1848, 462,889 ; 1849, 532,142; 1850, 711,649 ; 

 1851, 928,181. Poolts Statistics. 



THE LOCK CONTROVERSY. 



THE London Practical Mechanics' Journal thus reports a paper 

 which was read before the Society of Arts, London, by Mr. Hobbs, 

 the ingenious American lock-picker : Mr. Hobbs began by showing 

 the construction of the old form of what is called the Egyptian or pin- 

 lock ; he also showed how readily, by obtaining wax impressions of 

 its vulnerable points, it readily yields up the treasures it would not 

 have touched by profane hands. The first modification of this form 

 was made about forty years ago, and another by Mr. Williams in 1839. 

 The objections to its use were pointed out by the facilities they all 

 afforded in being picked with false keys, which were easily made. 

 These, therefore, were in the abstract without utility for purposes of 

 perfect security. 



The ring-lock and the letter-lock were also shown to be in the same 

 predicament. Each ring was moved to that position where it was 

 found not to " bind," and retained there until all the rings had been 

 similarly treated, when the " open sesame " formed the best proof of 

 what he said. The letter padlocks, indeed, Mr. Hobbs alledged to be 

 really less secure than the pin-lock. He greatly amused those present 

 in detailing his adventures in picking a lock of something of this de- 

 scription in the Great Exhibition. There were a number of different 

 locks exhibited in one foreign department. Mr. Hobbs was there 

 with a friend. Mr. Hobbs took up the identical thing that was to 

 puzzle the nations, and examining it with educated lock-picking eyes 

 and fingers, soon conceived a means of overcoming the power ob- 

 jected to him. Cutting off a splinter from a wooden bench near him, 

 and quickly forming it to his purpose, and accomplishing that purpose 

 while his friend was otherwise engaging the attention of the exhibitor, 

 he brought forward the lock, and requested him to show the secret of 

 opening it. The exhibitor twisted the rings about, and got the letters 

 into their proper order. " There !" said the exhibitor. But the 

 charm had no effect. The exhibitor, in despair, consulted his memo- 

 randum. That was the magical word there was no doubt but the 

 cause of the non-success was inexplicable, until Mr. Hobbs kindly 

 explained, that in less than the three minutes in which he began and 

 finished his manipulations, he had discovered the key-note, and had 

 altered it! Mr. Hobbs showed the construction of the celebrated 

 Bramah lock, which he had succeeded in picking to the pocket-loss 

 of 200 to the celebrated and too confident patentee. Mr. Hobbs 



