254 REPORT— 1880. 



of gas are passed, often imperceptibly, throngli the same burner. In most 

 of the burners tested for the purposes of this Report, and which are not 

 provided with means of checking the pressure, it will be seen that about 

 twice as much gas is passed through the burner at 1'5 inches pressure as 

 is passed through at 0*5 inch pressure, and the pi'essure in the mains often 

 Tai'ies more than this. The amounts of gas passed through a burner 

 without obstruction for checking pressure with and without a governor at 

 different pressures is shown in the following table : — 



Single-burner governors are now made by Sugg, Peebles, "Wright, 

 Bori-adaile, and others. Many of these regulate the pressure by the rising 

 and falling of a small cup or cone fitting loosely in a receptacle through 

 which the gas passes on its way to the burner, and they are of a size 

 which does not obstruct the downward light, and of a form which does 

 not offend the eye. Several of these have been tested at pressures varying 

 from half an inch to three inches. From the exigencies of their construc- 

 tion they do not act absolutely perfectly, but at pressures vai-ying from 

 one inch (at which most of them are constructed to commence to act) to 

 thi'ee inches the amount of gas they allow to pass to the burner does 

 not vary more than half a cubic foot per hour. Such gov^ernors are of 

 very great service, not only in preventing waste of gas, but also in very 

 nearly securing \Vhat is so essential to the development of the maximum 

 amount of light, ft uniform supply of gas to the burner. 



Report of the ' Committee, consisting of Dr. G-ajsigee, Professor 

 ScHAFER, Professor Allman, and Mr. Geddes, for conducting 

 Palceontological and Zoological Researches in Mexico. Drawn 

 up by Mr. Geddes {Secretary). 



In pursuance of the plan for carrying on certain geological and zoological 

 explorations in Mexico (of which I gave some account in my application 

 for a grant from the Association last year), I sailed from Liverpool on 

 September 10th, 1879, and arrived at the city of Mexico on October 10th. 

 Besides the general object of a naturalist's first visit to the tropics, 

 that of obtaining a more general view of animated nature, I proposed 

 undertaking certain specific researches : — 



1. To examine some of the deposits of fossil bones in the Valley of 

 Mexico, of which so many accounts had been given me by eye-witnesses,, 

 and to ascertain their age and contents. 



2. To fill up such leisure as might remain from that inquiry with a 

 study of the completely unknown microscopic life of the great lakes. 



3. To make a general collection. 



