Question

Is six's maximum and minimum thermometer a weather instrument?

Answer 1

Yes, It is weather or meteorological instrument which is used to measure the maximum and and minimum temperatures of the day.

Answer 2

Six's ThermometerThe thermometer on the right is a special one for recording maximum and minimum temperatures. All Six's thermometers have one long 'U' shaped tube. This can be clearly seen in the image further down the page.There is a bulb of alcohol at the top of the tube on the left. This cannot be seen on this thermometer. The alcohol expands or contract as the temperature changes. It then push round the indicator liquid to show the temperature. This example has no mercury, and is therefore safer.You get to see the temperature twice, it should show the same temperature on both scales. Both Celsius scales show 19 °C.The Marker PinsSo that the Maximum (hottest) and Minimum (coldest) temperatures can keep be recorded there are two small steel pins. 
When the temperature rises, the marker 'pin' in the right hand column is moved. It will stay there until you reset it. You read the bottom of the 'pin'. This example is 28°C.
When the temperature falls, the marker in the left hand column will be moved to show the minimum temperature. Read the 'pin' at the bottom point. This example is 16°C. See more about reading the scales below.Reading the ScalesThe close-up of a part of the scales on the right shows how they are reversed. 
The right hand scale, for the maximum temperature, is the 'normal' way up. The larger numbers are at the top. Below the zero are the minus numbers (shown here in red).
The left hand scale, for recording the minimum temperatures, is reversed. The larger numbers are at the bottom. The minus numbers are above the zero (see the plus and minus signs).
When reading the temperatures that the pins were left at, always start at the zero and look carefully whether the number should be a positive number or a negative number.