70 MASSACHUSETTS HORTICULTUEAL SOCIETY. 



glass equal to that of foreign; competitors is the higher cost of 

 labor, but improved methods of manufacture will soon equalize 

 these matters. The advantages of foreign over domestic glass are 

 chiefly greater clearness, toughness, or strength, and absence of 

 waves. 



Methods of Glazing, etc. There is only one perfect method of 

 glazing for greenhouse work, and that is with light wooden bars, 

 and the glass bedded in suitable putty. The bars should be so 

 rabbeted as to leave a V shape, the putty being rubbed into the V, 

 and the glass then rubbed and pressed down firmly, until the lower 

 side rests on the sharp edge of the wood, and solid zinc shoe nails 

 or other suitable points are driven into the bar above the glass to 

 prevent its displacement. The surplus putty both above and 

 below the glass is then carefully cut away, and in painting, the 

 paint should be laid on thickly over that putty which may be 

 exposed on the upper side between the glass and the bar, and also 

 on the glass which is directly over the bar. This effectually 

 preserves the putty in the joints from the detrimental action of 

 the atmosphere. 



A system which, at first sight, and to the uninitiated, appears 

 to have extraordinary merits, and yet which yearly causes a great 

 waste of capital, and is the source of great annoyance to those 

 who employ it, as well as regret to those who have innocently 

 advised its use, is that known as the metallic glazing. There are 

 man}' systems of such glazing on the market, both patented and 

 otherwise, but, ray friends, I cannot advise you too strongly 

 against the use of any one of them, or any so-called improvement 

 or modification of them. 



In order that you may realize the defects in this system, I will 

 ask your attention to the following points; First, because of the 

 unyielding surfaces of both glass and metal (soft sheet lead 

 excepted), it is impossible to get a perfect contact one with the 

 other, and without perfect contact a perfect and air-tight joint 

 and security of the glass is impossible. An air-tight joint may be 

 made by the intervention of sheet rubber, sheet lead, cotton 

 saturated with white or red lead, and man}' other substances, but it 

 is only temporary, as the effects of moisture and variation of 

 temperature will soon cause decay on the one hand, and the 

 continual friction, caused by the difference of expansion of the 

 metal surfaces and the glass will soon wear away the intervening 

 packing. This continual friction also causes a wearing away of 



