68 



These may usefully be compared with the general means 

 of observations on the outside seas, the Mediterranean and 

 Red Seas. 



The Mediterranean shows a mean specific gravity in its 

 eastern basin of 1'029 — 30, and a mean temperature of 

 63° — Q6° F., or less than those of the canal; and the air at 

 Port Said, on land, has a mean temperature of 68°'9, or 

 about the same as that of the canal. 



The Red Sea is stated to have a mean specific gravity in 

 Suez Bay of 1'027, or less than that of the canal water, a,nd 

 a mean temperature of 71°, or higher than the same; and 

 the air at Suez, on land, has a mean temperature of 6 9° "5, 

 or somewhat higher than that of the canal. 



The mean temperature at Ismailia, on land, appears to be 

 68°'9 F., or about the same as that of the canal. 



These points tend to show that the warmth of water and 

 air of the canal probably come from the Red Sea, and not 

 from the land nor from the Mediterranean Sea, and that this 

 is borne along its waters by various currents and tides from 

 the south to the north end. 



The mean density of the canal water exceeds that of the 

 outside seas at either end by 1'039 to 1*027, and the cause of 

 this increase has been generally believed to be due to the 

 increased evaporation of the water of the canal by the in- 

 creased sun's heat and dryness of the air of the country. 



Now the highest mean density of the canal water was 

 found in April, 1-0434, coincident with moist N.W. winds 

 from the Mediterranean, and low mean humidity of 63 from 

 the absence of Nile floods over the eastern delta. 



The lowest mean density was seen in October, 1"0345, 

 coincident with dry N.E. winds, higher mean humidity of 

 67 from moisture of the air by the Nile floods being out 

 over the flats of the adjacent country. 



According to scales of mean temperatures on land the 

 greatest density from evaporation ought to occur in July, 

 which has a mean temperature at the stations of 82°*8 F., 

 and the least density to be found in February, with its 

 mean temperature of 55°"4 on land. On the contrary, the 



