THE OBSERVATORY OP ST. MARTIN, ISLE JESUS, C. E. 287 



consists of one drachm of starch, boiled in one ounce of distilled 

 water, to which is added when cold 10 grains of the Iodide of Potas- 

 sium — this is spread on sized paper which is found to answer better 

 than bibulous or unsized paper, for the solution is more equally distri- 

 buted over the surface, whereas on bibulous paper it is .very difficult 

 to spread the solution equally. It is cut into slips of about 3 inches 

 long and 5 inches wide — having been previously dried in the dark it 

 is also requisite, to keep it dry and free from light. "When required 

 one of these slips is placed 5 feet from the ground and shaded from 

 the sun and rain, — another of these slips of ozone paper is elevated 

 and exposed at an altitude of 80 feet, for the purpose of comparison. 

 It is also well to place slips of this prepared paper in the vicinity of 

 any vegetables, which may be affected with disease, for instance 

 during the prevalence of the potatoe rot. 



A Microscope and apparatus for the examination of snow crystals 

 and also obtaining copies by the chromotype process, is also provided. 



The Electrical Apparatus. — This consists of three parts : a hoist- 

 ing, a collecting and a receiving apparatus. 



The hoisting apparatus consists of a pole or mast 80 feet high. It 

 is in two pieces, but is spliced and bound with hoop iron, and squared 

 or dressed on one face for about six inches. It is dressed in a 

 straight line to receive cross pieces of two-inch plank, 8 inches wide 

 and 12 inches long, which are firmly nailed to the mast or pole about 

 three feet apart ; this serves as a ladder to climb the pole in case of 

 necessity. Each of these cross pieces is rehated to receive pieces of 

 inch board 4 inches wide, and placed edgeways in the rebate, extending 

 from the top to the bottom of the pole, and forms a sort of vertical 

 railway ; these pieces are also grooved or rebated to receive a slide, 

 which runs in these grooves and carries the receiving apparatus. 

 From the top of the sliding piece passes a rope over a pulley fixed at 

 the top of the mast, and from it to a roller and windlass, by which 

 means the collecting lantern is raised or lowered for trimming the 

 lamps. It has also been used for the purpose of placing the ozonometer 

 at that height (80 feet.) The lower part of the mast or pole is fixed 

 into a cross piece of heavy timber, and is supported by four stays. 

 These cross timbers are loaded with stones, and are thus rendered 

 sufficiently firm. 



The collecting apparatus consists of a copper lantern 3 inches in 

 diameter, 5 inches high. (See top of mast Gr, fig 1.) The bottom is 

 moveable and the lamp is placed in it by the means of a small copper 



