QUESTIONS FORMING A COMPLETE INDEX. 



xxffl 



LESSON LXV. 



Snow, why is it warm, though 

 white garments are cool 442 



Snow, why is it always on the tops 

 of high mountains ... ... 443 



Snow-line, what is meant by the ... 445 



Snow, what is red 446 



So } a- water, why does it effer- 

 vesce 802 



Soils, why are clayey unfavourable 

 to vfge-tation ... ... ... 1160 



Soils, why are sandy unfavourable 

 to vegetation 1162 



Soils, why are chalk unfavourable 

 to vegetation 1162 



Soils, why are mixed favourable to 

 vegetation 1163 



Soils, why do farmers manure 

 their land 1165 



Soot, why should it be prevented 

 from accumulating at the bot- 

 tom and sides of sauce-pans ... 205 



Soot, what is it 290 



Sound, what is it 716 



Sounds, what causes the air to pro- 

 duce 717 



Sounds, how do we know that they 

 are produced by vibrations ... 718 



Sounds, how do we know that 

 without air there would be none 719 



Sounds, how are the vibrations of 

 sonorous bodies imparted to the 

 air 720 



LESSON LXVI. 



Sounds, how rapidly do the vibra- 

 tions of travel 721 



Sounds, do all sounds travel at the 

 same rate t 722 



Sounds, why are bells nnd glasses 

 stopped from ringing by "touch- 

 ing them with the finger 723 



Sounds, why does a cracked bell 

 give discordant 724 



Sounds, why do we see the flash of 

 a gun before we hear the report 725 



Sound, why does the inarching of 

 long ranks of soldiers appear to 

 be irregular 726 



Sound.*, what are the numbers of 

 vibrations that produce various 727 



Sounds, why does the length of 

 a wire or string influence the 

 sounds it produces 728 



Sound, why does the tension of a 

 wi re or string affect its vibrations 729 



S.iund, why are some notes low 

 iid solemn, and others high and 

 quick 730 



Sound, why can our voices be 

 heard at a creator distance when 

 we speak through tubes ... ... 731 



Sound, is air a good conductor ... 732 



S'lunds, why can we hear them at 

 a greater distance on water than 

 on land ... ... ., 733 



LESSON LXV1I. 



Sound, why do sea-shells give a 

 murmuring noise when held to 

 the ear 734 



Sound, why can people in the arc- 

 tic regions converse when more 

 than a mile apart 735 



Sounds, why do savages lay their 

 heads upon the earth to catch 

 sounds 736 



Sounds, why can church clocks be 

 heard striking more plainly at 

 some times than at others ... 737 



Sound, why may the scratching of 

 a pin at one end of a long pole 

 be heard at the opposite ex- 

 tiemly 738 



Sound, why is the hearing of deaf 

 persons assisted by ear-trumpets 739 



Sounding-boards, why are they 

 used to improve the hearing of 

 congregations 740 



Sounds, why, when we are walk- 

 ing under arches or tunnels, do 

 our voices appear louder ... 747 



Spark, what causes it when a 

 horse's shoe strikes against a 

 stone 340 



Specific gravity, what is it 789 



Spiders, why have they the power 

 of spinning webs ... ... ... 1082 



Spider*,why may fine weather be ex- 

 pect-d when they build their webs 1108 



LESSON LXV1II. 



Spiders, wby may wet weather be 

 expected when they hide ... 1109 



Spiders, why may wet weather be 

 expected when they break off 

 their webs and remove them ... 1113 



Spider, why, if the webs of the 

 gossamer fly about in autumn, 

 may east winds be expected ... 1124 



Spiders, gossamer, why can they 

 float through the air ... ... 1125 



Spinal cord, what is the ... ,.. 952 



Spinal cord, why is it placed in the 

 back-bone ... 953 



Spinal-cord, how do the branches 

 pass out from it 954 



Spontaneous combustion, what sub- 

 stances are liable to it 317 



Spontaneous combustion, has it 

 ever occurred in living bodies ... 319 



Spontaneous combustion, why doea 

 it occur in the case of the drunk- 

 ard 320 



Spoon-bill, why has it a long ex- 

 panded bill, lined with sharp, 

 muscular points 1045 



Spoon-bill, why has it long legs ... 1046 



Squint, why do some people ... 967 



Starch, what is it 1202 



Star-lit nights, why are they usually 

 colder than cloudy nights ... 350 



Stars, why do they twinkle ... 484 



