Infinitescroll to finish after a certain number of posts - jquery-masonry

Question

I am using Paul Irish's infinitescroll with masonry js on a wordpress site. It is a site with a lot of content. I want infintescroll to stop adding new content when it reaches post number 40 and to give the "No additional items" message at that point. I tried to customize the wordpress loop to only return 40 posts but that did not seem to work.
I thought that maybe one of the options in infinitecroll might do the trick but the infintescroll documentation is very sparse. For example, there is an infinitescroll option in the "loading" init section called "finished: undefined" Is it possible to change that parameter to stop the scrolling after a certain number of content items?
Is there some other obvious way to control when infinitescroll stops loading new content?
Any assistance would be greatly appreciated.

Answer 1

In the Administration -> Settings -> Reading you can set Blog pages show at most to 40.
With code:
Two ways I've done Masonry by numbers like your question I've had success with the following:
limit posts_per_page in your query arguments
$args = array(
'posts_per_page' => 40,
'offset' => 5,
'orderby' => 'post_date',
'order' => 'DESC',
'exclude' => 'none',
'post_type' => 'post',
'post_status' => 'publish',
'suppress_filters' => true
);
$posts = new WP_Query( $args );
if ( $posts -> have_posts()) {
while ( $posts -> have_posts() ) : $posts->the_post(); {
//do stuff with the posts returned here
}
}
or by incrementing:
$counts = 0 ;
$posts = new WP_Query( $args );
if ( $posts -> have_posts()) {
while ( $posts -> have_posts() ) : $posts->the_post(); {
//do stuff with the posts returned here
$counts = ++;
if($counts == 40) { return }
}
}