Problem of trying to get gmail atom feed in ruby

I write some simple ruby code to try to get gmail atom feed:

http = Net::HTTP::new('', 443);
http.use_ssl = true ;
http.start {
    request ='/mail/feed/atom"');
  response = http.request(request)
  puts response.body

But it is fail...

warning: peer certificate won't be verified in this SSL session
/usr/lib/ruby/1.8/net/http.rb:2097:in `error!': 400 "Bad
Request" (Net::HTTPServerException)
  from /usr/lib/ruby/1.8/net/http.rb:2106:in `value'
  from /home/carfield/respository/atomtest.rb:13
  from /usr/lib/ruby/1.8/net/http.rb:543:in `start'
  from /home/carfield/respository/atomtest.rb:9

Anyone know how can I solve it? Done a brief google search doesn't