Complex sentence: The fuel was forced up to the lamp by air and the Keepers had to pump the air contain or up every hour or so this in turn presurised the paraffin container to force the fuel to the lamp.
Split into simpler sentences: The fuel was forced up to the lamp by air and the Keepers had to pump the air container up every hour or so. This in turn presurised the paraffin container to force the fuel to the lamp.