674 THE POPULAR SCIENCE MONTHLY. 



some unknown law, a law perhaps not of a meteorological but of an 

 astronomical origin. 



We should remember, however, the imperfections and probable 

 errors of the old tables. In former times due care was not taken in the 

 construction and verification of the thermometers. Making every 

 allowance for this, we may perhaps admit that the conclusion at which 

 we have arrived cannot be very far from the truth. 



-**-- 



AS REGARDS SPIDERS. 



" "Y^T""^"^ can tnere ^ e interesting in that commonplace, repulsive 

 V V little creature, which infests our houses, annoys us by its pres- 

 ence, and shocks our sense of decency with its filthy webs in that cruel 

 little monster, whose whole life is employed in weaving snares to entrap 

 unwary flies ; lying in wait for them in dark, damp corners of crevices, 

 murdering them remorselessly when they are caught in its toils, and 

 then sucking their life's-blood ? The house-spider, indeed ! Why, we 

 sweep it from the very face of Nature wherever we find it, together 

 with its chamber of horrors ; and it must indeed be some strong temp- 

 tation that would induce one to defile one's hands by contact with a 

 creature the very idea of which suffices to inspire terror and disgust." 

 It is true that spiders are not very lovable creatures, but this is a 

 prejudiced statement. Spiders are only repulsive as long as we are 

 ignorant of them. If we will but stop to observe their wonderful 

 structure and their ingenious ways, we shall quickly get rid of these 

 foolish notions, and find that the creature will richly repay us for the 

 time and pains of studying it. Spiders have a great deal of character, 

 and, although very savage, they have also much in common with the 

 vaunted heads of creation. Let us consider some of their peculiarities. 

 Spiders were formerly classed as insects, and they are commonly 

 so regarded still, but this is an error. Insects have but six legs, while 

 spiders have eight ; there is a division in insects between the head and 

 the trunk, but spiders have no separate head, the head and thorax 

 being fused together, under the name of cephalotlwrax. In many kinds, 

 body, thorax, and abdomen, are so closely merged together that 

 their parts cannot be traced. Again, insects undergo metamorphoses 

 or transformations in their growth, while spiders do not. They belong 

 to a group which includes mites and scorpions, and is named the 

 AracJmida. There are multitudes of different kinds, and they vary in 

 dimensions from the size of a grain of sand to several inches in diame- 

 ter. Some spiders are met with in all parts of the world, and some are 

 limited to special localities ; some live in the fields, and others on the 

 water; some dwell habitually in houses, and others are driven in by 



