112 



observed similar phenomena. One instance he mentioned was of a very singular 

 character : an. engineer on board one of H.M. steamships, observed that a very 

 strong connecting-rod attached to the side valves, in the course of a very short 

 time, broke, or rather twisted, off ; others were substituted, every care was taken 

 in their manufacture, and the best iron procured, but with hke results ; at length 

 he tried what is termed in trade as " faggoting," which means the welding a number 

 of bars together ; but still the same accident occurred, and whether the iron was 

 fibrous or laminated, the fracture always presented a crystalline structure, the 

 molecules having arranged themselves differently during the repeated percussions 

 which acted upon them ; at length, it suggested itself to him to have a hole 

 drilled through the rod, after which the bar lasted for years without undergoing 

 any perceptible change. 



Now, how the hole in the centre prevented the crystallisation of the iron and 

 its consequent fracture is a problem difficult to solve, unless we assume that it is 

 subject to the general laws of crystallisation, a nucleus or centre being first 

 formed, around which the different molecules arrange themselves until a perfect 

 form of crystaUisation is effected. 



This I have frequently found to be the case in the crystalhsation of salts 

 in solution :— for instance ; a sample of the iron hquor obtained from the Park 

 End Tin Works at our last meeting in the Forest of Dean, refused to crystalUse 

 although concentrated to a point at which crystallisation might reasonably be 

 expected ; but as soon as a small particle of the sulphate of iron was placed in 

 the liquid, crystallisation commenced, and continued uninterrupted. In this 

 way, I apprehend, the centre being removed from the bar, no crystaUisation could 

 take place, and the iron would preserve its fibrous or lammated structure. It is 

 a fact, also, observed by practical men, that, when iron, which has assumed the 

 crystalline structure is heated, and then gradually cooled (which is called 

 " annealing,") it again resumes its fibrous texture. 



LIST OF PLANTS OBSERVED. 



The following list of some of the rarer plants observed during the day, was 

 handed in by Mr. Hutchinson, and other members : — 



Trifohum medium. Onobrychis sativa. 



Mehlotus officinaUs. Genista tinctoria. 



Nardus stricta. Pyrola minor. 



Hehanthemum vulgare. Scrophularia Ehrhardti. 



Anthyllis Vulneraria. Trifolium medium. 



Orchis pyramidahs. Epilobium montanum. 



Chlora perfoliata. Circaea alpina. 



Aurantia arvensis. Sedum album. 



Hypericum pulchrum. Linaria minor. 



Geranium lucidum. Lycopsis arvensis. 



Ophrys apifera. Euphorbia exigua. 



Rhamnus catharticus. Typha latifoUa. 



Spartina stricta. Poa compressa. 



Agrostis vulgaris. Fedia dentata var. mixta. 



