His custom-made `` linnaeus-thermometer '' , for use in his greenhouses , was made by Daniel Ekström , Sweden 's leading maker of scientific instruments at the time and whose workshop was located in the basement of the Stockholm observatory .
His custom-made `` linnaeus-thermometer , '' to use in his greenhouses , was made by Daniel Ekström , then Sweden 's leading maker of scientific instruments . Eckstöm 's workshop was in the basement of the Stockholm observatory .