256 The Ohio Journal of Science [Vol. XIX, No. 5, 



the wires were simply twisted together and welded in a high 

 temperature furnace. The other end, from which the lead wires 

 ran to the recording instrument, was covered with a wooden 

 handle. This end, the cold junction, was connected with 

 a small open coil of fine insulated wire inside the handle 

 and had to be kept at the air temperature the same as the 

 recording instrument, as well as dry and clean. This limited 

 the use of the thermocouple to a length of eight feet in a hole. 

 In many cases the steam around the vents was so thick as to 

 prohibit its use at all. We partly overcame this in some cases 

 by wrapping the cold junction in a towel to keep the steam from 

 condensing in the coil. While this limitation made no differ- 

 ence in narrow throated fumaroles, it was a serious handicap 

 in dealing with large crater-like vents where one could see for 

 50 or 60 feet down the hot throat. In one of the " Twins, " for 

 example, where the temperature at the surface was 309 C. 

 we wondered what the temperature would be 60 feet down the 

 hole. 



The recording instruments, moreover, had to be kept dry and 

 at the air temperature. The ground for a considerable distance 

 around any area of activity was so hot that correct results 

 could be obtained only by keeping the recording instrument off 

 the ground by setting it on a packsack, sample box or old coat. 



Besides thfese difficulties, there was the personal danger of 

 getting too close to the hot steam, or of breaking through the 

 thin crust over a line of fissures. In many cases we were not 

 able to get near enough to use our instruments at all. If there 

 was a strong and constant wind, we could work quite close to the 

 orifice on the windward side without much danger, but we had 

 to be very careful not to get close enough to produce a back 

 draft or undertow against our bodies. This happened several 

 times in low temperature "steamers." In such cases we had 

 to throw ourselves away very quickly to avoid serious injury, 

 for if one should get into a flare-back from one of those which 

 recorded 300 C., he would be in great danger of terrible injury. 



While some of -the vents are mild mannered "steamers" 

 emitting principally water vapor, the vapor from others appears 

 altogether dry and consists largely of other gases which are 

 generally disagreeable and ^ometimes, as for example when 

 heavily charged with hydrofluoric acid,* dangerous if inhaled. 



*Analyses of the gases given off from the vents have been begun by Dr. E. S. 

 Shepherd of the Geophysical Laboratory. 



