1 In the mercury barometer, atmospheric pressure balances a column of mercury, the height of which can be precisely measured. 2  Of the many different varieties of mercury barometers, most variations arise from different techniques for measuring the height of the mercury column.
Recognizing the Symptoms of an HIV Rash. 1  1. Check for a rash that is red, slightly raised, and very itchy. 2  2. Note if the rash appears on your shoulders, chest, face, upper body, and hands. 3  3. Pay attention to other symptoms that may occur when you have HIV rash.  4. Be aware of the causes of HIV rash.
The earliest signs of an HIV infection are flu-like symptoms that include fever, rash, swollen lymph nodes, headache and fatigue, according to Mayo Clinic. These symptoms usually appear between 30 and 60 days after a person has been infected, and they may be mistaken for another viral infection. Continue Reading.