162 EIGHTH REPORT — 1838. 



pletes eight rivets of three-fourths of an inch in diameter in a minute, 

 with the attendance of two men and two boys to the plates and rivets ; 

 whereas the average work that can be done by two riveters and one 

 liolder-ou and a boy, is 40 three-quarter rivets per hour ; the quantity 

 done in the two cases being 40 to 480, or in the proportion of 1 to 12. 



On a Steam-engine Boiler. By J. Price. 



The author exhibited a model of a steam-engine- boiler of 18 horse 

 power which is at work daily at the Durham Glass-works, Gateshead, 

 and described its peculiar construction and advantages in regard to 

 safety and cheapness. 



He states, that by the construction of the flues the whole of the 

 heat is rendered available. Owing to the draught, the dust that accu- 

 mulates in the flues is only ten pounds per week. 



There are two cocks in the laggings of the furnace, and three along 

 the bottom of the boiler to let off water and sediment when required ; 

 in consequence of Avhich there have only accumulated 29-|lbs. of thin 

 mud in six weeks, which contains 2 oz. 6\ drachms of fine poAvder. 

 He mentions, as one principal advantage of this boiler, the impossi- 

 bility that either flues or boiler can collapse. 



A steam safety-valve is applied in the form of a ball in a cup which 

 rises from its seat and allows the steam to escape so soon as it comes to 

 within one pound of the safety pressure ; it is covered with a cap, which 

 is secured by nuts within the boiler, and cannot be removed or 

 weighted without cooling the boiler: consequently it is beyond the 

 reach of the working engineer, who has his own valve to regulate as he 

 likes. 



A New Rotatory Steam-Engine. By S. Rowley. 



It was stated by Mr. Evans, that the novelty in this construction 

 consisted in the excentric being on1;he inside. 



Remarks on the Construction of Steam-Boilers. By W. Greener. 



Mr. Greener stated his opinion, that the accidents which happen to 

 "steam-boilers are principally due to defect in the material of which 

 they are constructed. He detailed several experiments made on slips 

 of iron cut from plates of different quality. He found that slips cut 

 latitudinally from a plate sustained less pressure by 30 per cent, than 

 slips of the same dimensions cut longitudinally ; in some cases the dif- 

 ference was much greater. He also had immersed plates in a mixture 

 of sulphuric acid and water, and found that the injury done in twenty- 

 four Jiours varied from 6^ to 15 per cent, of the original strength. 

 Many boilers will stand so long as the form remains perfect ; but should 



