Account of a Nortb-Eajl Storm, 27$ 



Four feet of the tube and the lower wedge are in general 

 loft; but the upper wedge may be employed for new charges, 

 becaufe it is never damaged. 



Obfervathn. 



1 2th, This method, the fucccfs of which is proved, de- 

 serves, no doubt, to be known by all thofe engaged in great 

 undertakings, and who have frequent occafion to apply it *• 

 It is, perhaps, fufceptible of being modified; and it appears 

 to me that, without employing the impermeable tube, a var- 

 us Hied cartridge might be ufed, with a flexible tube proceed- 

 ing from it, lodged in the groove between the two wedges, 

 and then rifing above the water. 



Fire alfo might be conveyed to the powder below the wa- 

 ter by means pf a ftrong difcharge of electricity ; but little 

 can be expected from this method in the hands of workmen. 



In the laft place, the lower wedge might be made of hard 

 and very dry wood. 



13th, But in whatever manner this method may be em- 

 ployed it will not require great expenfe, and it may be ufed 

 with great advantage for deepening ports, rendering certain 

 harbours more convenient and fafe, and for freeing rivers 

 and ftreams from thofe rocks which obftrucl: their courfe and 

 impede the navigation of them. 



XLVL Account of a North- Ea/l Storm, or Memorandums to- 

 wards a Theory of the Winds in the Region between the 

 Gulf- Stream and the Great Range of Mountains \ . 



o 



N the Atlantic coaft of America north-eaft ftorms begin 

 in the fouth-weft, and proceed thence to windward at the 

 rate lbmetimes of about one hundred miles an hour. It has 

 been remarked long ago by Dr. Franklin, that ftorms from 

 the north- eaft, on the eaftern fide of this continent, begin in 

 the oppofite point, or to leeward. Whether this rule uni- 

 verfally obtains may perhaps as yet admit of fome doubt: 



• M« Daniel Thunberg employed the fame means to raife large blocks 

 pf ftone from the bottom of the water. For this purpofe a hole is bored 

 in the block with a miner's borer to the depth of twenty or twenty-five 

 centimetres. Two wedges are introduced into it, forming by their junc- 

 tion a cvlinder Co as to fill the hole. Several blows aie then ftruck on the 

 iron bar which adheres to the upper wedge: the two wedges are thin 

 clolely Iqueezed together, and the block is railed out of the water by means 

 d a windlals and a cord attached to a ring fixed in the lower wed^e. 



f Cpmmunicared by Dr. Mitchill. 



but 



