214 



METHODS OF COMMUNICATION FOR FOREST PROTECTION 



Where maximum and minimum dimensions are shown the dimensions shall be 

 within the limts specified. Where limits are not shown the dimensions shall be 

 approximate. 



The diameter of the thread shall be such that at least two revolutions of the 

 insulator will be required to tighten it on the standard insulator gauge, and when in 

 this position the end of the insulator gau^e shall not be more than one-eighth of an 

 inch from the crown of the insulator. 



4 threads to the inch 



Specifications 6 Design of Forestry Branch standard pony glass insulator 



The thread of all insulators shall be smooth and of uniform pitch. The thread, 

 shall be well centred in the insulator so that, when in place on the standard insulator 

 gauge, the gauge will not touch the inner surface of the petticoat. 



Insulators conforming in all other respects to the requirements of these specifi- 

 cations, but having on the lower edge of ,their petticoats a series of projecting points, 

 may be accepted under these specifications. 



Finish. The insulators shall have a finish ensuring, so far as is consistent with 

 the best commercial practice, smooth even surfaces and freedom from flaws, cracks, 

 blow-holes, sharp edges, and other defects. 



7 Specifications for Split Tree Insulators 



Material. Split tree insulators .shall be made of the best grade of insulator 

 porcelain. 



Finish. The surface shall be prown-glazed except the faces which are to be 

 placed in contact in .attaching the insulator around the line wire. These may be left 

 white and unglazed. The glazed finish shall be smooth, without rough spots, cracks, 

 sharp edges, or other defects. 



