VOL. XLIII.] PHILOSOPHICAL TRANSACTIONS. 123 



amples seem sufficient to show how manageable the magnetic virtue is, in respect 

 to its direction ; and how defective most of the hypotheses are, which have been 

 raised to account for the phenomena of the loadstone. 



Of some very Curioui fVasps* Nestx made of Clay in Pennsylvania. By Mr. John 



Bartram. N° 476, p. 363. 



Mr. Bartram sent from Pennsylvania 2 sorts of curious wasps' nests made with 

 clay, which are commonly built against the timber under the roofs of houses and 

 pales, to shelter them from the weather. They feed, as the bees, on flowers ; 

 but whether they sting like them is not yet known. 



The plain clay nest is fabricated by a small black wasp, of the same species of 

 that in fig. 10, pi. 2, but less, having a speck or stripe of yellow in his tail ; and 

 the cells are made 4 or 5 together, joining side by side to each other. But the 

 clay nests, that are so elegantly wrought, are built by a purplish black wasp, 

 such as represented fig. 1 1 : after one cell is formed they stop it up, and join an- 

 other to its end, and then add another to that ; which makes these wrought clay 

 fabrics longer than the plain ones. -' 



Their method of working is much alike, and it is very diverting to see therti 

 at it : their art and contrivance is wonderful ; and, as if it was given to cheer 

 them at their labours, they make a very particular musical noise, the sound of 

 which may be heard at 10 yards distance. 



Their manner of working is, to moisten clay, and temper it up into a little 

 lump, of the size of swan-shot. This they carry to build with ; they begin first 

 at the upper end of the cell, and work downwards, till it is long enough to coiv 

 tain the nymph or chrysalis : afler they have spread out the little lump in a 

 proper manner to form their little fabric, they set up their musical notes, and 

 return to temper and work up more clay for the next course. Thus they con- 

 tinue alternately singing and working, till a cell is finished ; which is made deli- 

 cately smooth withinside ; then, at the further end of each cell, they lay an egg; 

 after this, by surprising instinct, they go and catch spiders, and cram the cell 

 full of them : but it is fiirther wonderful to observe, that they only in some 

 manner disable the spiders, but not kill them ; which is to answer two purposes; 

 first, that they should not crawl away before the cell is finished ; and next, that 

 they may be preserved alive and fresh till the egg hatches, which is soon. 



The spiders, by wonderful instinct, are provided for the embryo to feed on : 

 having stored up sufficient for its support, she very securely closes up the cell, 

 and then proceeds to build the next in the same manner. 



The maggot or embryo, having eaten up all its provision before October, pre- 



• ITiese insects belong to the Linnean genus Sphcx. 

 r2 



