62 REPORT— 1844. 



It appears therefore that the annual and diurnal variations derived from 

 the observations at Greenwich present a most satisfactory accordance with 

 those at Toronto in those points which were brought most prominently be- 

 fore the Association at York, and to which the attention of the Section was 

 especially called, viz. — 



First, in regard to the diurnal variation : 



1. The vapour tension and the force of the wind have each a minimum, 

 and the gaseous pressure a maximum, at or near the coldest hour of the day. 



2. The vapour tension and the force of the wind have each a maximum, 

 and the gaseous pressure a minimum, at or near the warmest hour of the day. 



3. The diurnal march of each from the minimum to the maximum, and 

 from the maximum to the minimum again, is continuous, like that of the tem- 

 perature, without any interruption deserving of the name. 



4. At Greenwich as well as at Toronto the diurnal variations of the vapour 

 tension and of the gaseous pressure, produce by their combination the double 

 maxima and minima of the diurnal oscillation of the mercury in the barometer. 



Secondly, in respect to the annual variation : 



The annual march is somewhat less regular at Greenwich than at Toronto, 

 being derived from the observations of a single year only ; but Ave have the 

 same general features : a minimum of temperature and vapour-pressure, and 

 a maximum of gaseous pressure in the midwinter; and a maximum of tempe- 

 rature and vapour pressure, and a minimum of gaseous pressure in the mid- 

 summer. All the summer months are characterised by the + sign in the 

 vapour, and by the — in the gaseous pressure ; and all the winter months by 

 the — sign in the vapour, and the -i- sign in the gaseous pressure. 



I am unable at the jDresent moment to pursue the comparison of the Green- 

 wich and Toronto results in many other points in which I can perceive that 

 the interest would prove an ample repayment for the time so employed. But 

 I may hope to enjoy some future occasion of resuming the subject under 

 more favourable circumstances in respect to leisure than I can at present 

 command. 



Report on some recent Researches into the Structure, Functions and 

 (Economy of the Araneidea made in Gh'eat Britain. By John 

 Blackwall, F.L.S. 



In essaying to give an epitome of some investigations recently made in this 

 country relative to the organization, physiology and ceconomy of the Araneidea, 

 I shall endeavour to accomplish the undertaking in as compendious a m.anner 

 as may be deemed compatible with a perspicuous statement of the various 

 facts to be detailed, distinguishing those already before the public from such 

 as are not by references to the works in which they have appeared. 



Without further preface, I proceed to the consideration of those remark.ible 

 appendages termed scopidce or brushes, with which the tarsi of numerous spe- 

 cies of spiders are provided. This apparatus, consisting of coarse, compound, 

 hair-like papillfe either distributed along the inferior surface of the tarsi or 

 situated immediately below the claws at their extremity, bears a close analogy 

 to the tarsal cushions of insects, enabling its possessor to ascend the per- 

 pendicular surfaces of highly polished bodies and even to adhere to smooth 

 objects in an inverted position by the emission of a viscous secretion*. The 

 different plans according to which the papillae are disposed upon the tarsi are 

 respectively represented by two common IBritish spiders, Drassus sericeus and . 

 Salticus scenicus. 



* Transactionsof the Linnxan Society, vo). xvi. pp. 7CS,769. Researches in Zoology, p. 2S!). 



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