2kg sugar
1kg lemons
1.5l water

add water, sugar to pot.
if you have a citrus juicer, slice and juice all lemons into the pot.

sift through juiced halves and remove seeds
slice halves into half, and begin slicing lemons thinly. thicker slices may be preferred.  There is absolutely no one
who prefers seeds in their marmalade.

return lemon slices to the pot.

bring to rolling boil and stir often until peels are translucent and a drop test is passed.

seeds you've missed will brown and float to the top, skim as visible.  

drop test:  place a few drops of marmalate on a cool tea saucer.  if the marmalade thickens 
it is done