Pachyderm parallel put me in the picture on New York City weight

The Empire State Building, one of many skyscrapers that contribute much to the total weight of in New York City’s built infrastructure, roughly equivalent to 140 million elephants. Photograph: Brian Overcast/Alamy

Thank you for explaining that, at 1.68tn lb, New York City’s built infrastructure is roughly equivalent in weight to 140 million elephants (New York City is sinking due to weight of its skyscrapers, new research finds, 19 May). That makes it so much easier to visualise.
Mark de Brunner
Burn Bridge, North Yorkshire

• It would be even more helpful to know whether these are the larger, heavier African elephants or the smaller, lighter Asian ones.
Michael Robinson
Berkhamsted, Hertfordshire