New Series, December, 1905. 



365 



how fast these plants grow? What is needed to make them grow most 

 rapidly? When do they grow most, at night or in the day time, or just 

 as fast one time as another? I think you will find it good fun to try to 

 find out the answers to some of these questions. 



The best way to find out these things is to let the plants answer the 

 questions. First, then, we must have the plants. Get three small pots, 

 cans, or boxes. Fill each with earth, sawdust, or even fine chaff from the 

 barn will do. Plant three grains of corn in one can, five grains of oats 

 in another, and five grains of buckwheat in a third. If you do not have 

 these seeds, any other kind will do. Wet the soil of each with lukewarni 

 water and place near the stove. 



Now, while we wait for our plants to come up, we will make some 

 machines with which to measure how fast they grow. The girls may 

 make a machine like this, such as we have illustrated in Fig 4; if, how- 

 ever, they know how to use a jackknife or have a brother to make one 

 for them, they may prefer the one 

 shown in Fig. 3. The machine in Fig. 

 4 is a smooth, flat stick with inches, 

 half inches, and quarter inches marked 

 on it. When the little plant first peeps 

 above the ground, put the stick into 

 the soil beside the plant, pushing it 

 down until the zero mark comes just 

 to the tip. Put the plant back by the 

 stove and see whether the tip stays at 

 zero all night. You can make a ma- 

 chine for each plant and see which 

 grows the fastest. 



IVIany of you I am sure will like 

 to make a machine like the one shown 

 in Fig. 3. You will need some thin 

 pine boards, pins, thread, paper, a 

 jackknife, and gimlet to work with. 

 The long arm of the pointer is four 

 times as long as the short arm includ- 

 ing the pin. The tip of the pointer is 

 dipped in ink so that it will show more 

 plainly. A common pin is used as a 

 pivot at A on which the pointer must 

 swing freely. The long piece of paper with the pin holes in it is used so 

 that you can regulate the length of the thread to suit the distance from 

 the tip of the plant to the short arm of the pointer. The short bit of 

 paper is to attach the plant to the machine. Stick this bit of paper to 



Fig. 4. — A more simple arrangement 



for measuring the groivtJi of plants. 

 Try it. 



