332 History of Mechanical Inventions and 



the collision of its particles, both at its emission from the 

 sun, and at its refraction or reflection from solid bodies. The 

 experiments on which these results were founded, were exhi- 

 bited to the Honourable Lord Glenlee, and to Professor Rus- 

 sel, Vice-Presidents of the Royal Society of Edinburgh ; and, 

 in 1814, they were described to some foreign philosophers of 

 distinguished eminence. The author, however, was desirous 

 of extending his experiments before he gave them to the pub- 

 lic, and his memoir is accordingly still in MS. 



Art. XXX — HISTORY OF MECHANICAL INVENTIONS 

 AND PROCESSES IN THE USEFUL ARTS. 



1. Description of a simple Punt-Boat for saving time and labour. Ry 

 Andrew Waddell, Esq. F. R. S. E- Communicated by the Author. 



This Punt-Roat is shown in Plate V., Fig 12- It is 60 feet long, 16 feet 

 broad, and 4£ feet deep. 



It carries its lading upon deck, and it is for the purpose of transport- 

 ing stones and other materials for constructing wears or breakwaters, and 

 for removing obstructions in dry and bar harbours. 



In the interior of the boat below deck, there is a water-tight space 

 built on one side, occupying about one-third of the breadth of the boat, 

 and the whole of the length, which space has no connection with any 

 other part of the interior. 



In the bottom of this space there is an opening with a valve to shut at 

 pleasure, capable of admitting as much water in one minute, as will sink 

 down that side of the boat, and raise the other ; thereby forming an in- 

 clined plane, and admitting of the stones or other material on the deck of 

 the boat sliding easily overboard into the water, after the manner in which 

 a loaded cart is emptied. 



The boat will then instantly resume nearly its upright position, and the 

 valve being left open, the water that was admitted into the above mention- 

 ed space, will run out again to the level of the water without. The 

 valve is then to be shut, and any water that remains in the said space 

 pumped out in a few minutes , by means of a wide-chambered pump, and 

 the aid of one man. 



A boat of this construction will be most useful in forming breakwaters, 

 by dropping the stones at high water, or at any time in deep water, exactly 

 on the spot wanted ; but the above mentioned valve should be made to 

 open and shut with a screw, so that, should the lading be required to be 

 put overboard at different parts, the side of the boat might be sunk BO 

 further than to admit of a man sliding the stones down one after another. 



This boat, when light, draws about one foot and ten inches, and when 



